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Electric manipulation of magnetization is essential for the integration of magnetic functionalities in integrated circuits. Spin-orbit torque (SOT), originating from the coupling of electron spin and orbital motion through spin-orbital interaction, can effectively manipulate magnetization. Symmetry breaking plays an important role in spintronics based on SOT. SOT requires inversion asymmetry in order to have a net effect on magnetic materials, which is commonly realized by spatial asymmetry: a thin magnetic layer sandwiched between two dissimilar layers. This kind of structure restricts the SOT by mirror and rotational symmetries to have a particular form: an “antidamping-like” component oriented in the film plane even upon reversal of the magnetization direction. Consequently, magnetization perpendicular to the film plane cannot be deterministically switched with pure electric current. To achieve all-electric switching of perpendicular magnetization, it is necessary to break the mirror and rotational symmetries of the sandwiched structure.

When dielectric elastomer materials are used for power generation, bias voltage is applied at both ends of dielectric elastomer film, and there are equal amounts of heterogeneous charges on both sides of the film, so Maxwell electrostatic force is always coupled in the process of power generation. In order to investigate the distribution of Maxwell stress in dielectric elastomer material under electric field, the electrostatic model of dielectric elastomer generator is established in COMSOL finite element simulation software environment in this paper. The distribution of electrostatic force is studied from two aspects of theoretical derivation and simulation, and the magnitude and direction of electrostatic force are determined. The simulation results show that the Maxwell electrostatic force can be equivalent to the tensile force along the film plane and the extrusion force perpendicular to the plane, and they are the same.

The domain structures in the Co(0001) film with a thickness of 200 nm containing Bloch lines are studied in this work using the 3D micromagnetic modeling method. It is shown that Bloch lines include Bloch points in the cases when the domain walls are vortex-like. The transformation processes of domain structures containing Bloch lines are considered in the course of the film magnetization to saturation and subsequent decrease in the magnetic field to the zero value (for the fields lying either in the film plane or along the normal to the film). The configurations of magnetization in Bloch lines are analyzed. It is demonstrated that Bloch lines with both vertical and horizontal segments arise upon the application of magnetic field forming some angle with the film plane.

Perpendicular 90 kOe torquemetry analysis of magnetic anisotropy ( $K_{\mathrm {u\bot }}^{\mathrm {exp}}$ ) for L10-typed FePt granular media with various grain boundary materials (GBMs) was conducted. According to the analysis for granular films with a constant GBM volume of 30 vol% deposited at a high substrate temperature, $K_{\mathrm {u\bot }}^{\mathrm {exp}}$ was not dependent on the saturated torque coefficient of fourfold components ( $L_{4\theta }^{\mathrm {sat}}$ ) but was dependent on that of twofold components ( $L_{2\theta }^{\mathrm {sat}}$ ) originating from magnetic grains with $c$ -axes normal to the film plane. Furthermore, $L_{4\theta }^{\mathrm {sat}}$ mainly originated from FePt grains with $c$ -axes parallel to the film plane. $K_{\mathrm {u\bot }}^{\mathrm {exp}}$ also had a strong correlation with grain diameter ( $GD$ ) and degree of order ( $S_{\mathrm {in}}$ ). On the other hand, $K_{\mathrm {u\bot }}^{\mathrm {exp}}$ had no significant correlation with the melting point ( $T_{m}$ ) of the GBM, which indicates that the dominant factor affecting $K_{\mathrm {u\bot }}^{\mathrm {exp}}$ was not phase separation. Based on these evaluations, an increase of $GD$ caused an increase of $S_{\mathrm {in}}$ , regardless of the GBMs, which resulted in enhancement of $K_{\mathrm {u\bot }}^{\mathrm {exp}}$ for the FePt granular films.

Wurtzite AlN films with high Fe concentrations were deposited on Si(100) substrates using radio-frequency sputtering, and the growth process was investigated. X-Ray diffraction (XRD) analysis with parallel incident X-rays showed that a thick film (∼2.5 μm) had a non-polar a-axis orientation, similar to the films deposited on SiO2 glass substrates. Through powder XRD analysis, it was found that non-wurtzite fine crystals and/or amorphous materials formed during the initial stage of deposition, followed by wurtzite nucleation with various orientations of the axes, such as a, m, and r orientations. The XRD results also implied that the a-axis-oriented regions drastically increased with increasing film thickness. Scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy analyses suggested that one of the candidates for the non-wurtzite fine crystalline material was γ-Al2O3. STEM analysis also demonstrated that a-axis-oriented single-crystal grains grew from randomly oriented small wurtzite grains that increased in diameter with increasing deposition time. Al K-edge X-ray absorption near-edge structure results suggested that the electronic structure in the polar c-axis direction of wurtzite lying in the film plane developed with deposition time, thereby further supporting the findings of the XRD and STEM analyses.

For plastic spintronics, it has thus far been a challenge to develop a (magnetic nanostructures)/polymer heterostructure at low temperature due to the thermal sensitivity of polymers. In this context, half-metallic magnetite (Fe3O4) films of different thicknesses were coated on flexible polymethyl methacrylate (PMMA) substrates by reactive sputtering at 300 K. Grain size and thickness increased from ~10 nm to ~34 nm and 50 nm to 400 nm with an increase in the deposition time from 165 to 1335 s, respectively. Moreover, a sharp rise in grain size was observed when the thickness of the film reached 200 nm, and finally, saturation took place at 400 nm. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and X-ray photoelectron spectroscopy (XPS) studies confirmed the absence of the γ-Fe2O3 phase and thus the successful deposition of Fe3O4 thin films on the PMMA substrate. Parameters as such as Verwey transition (Tv) (~125 K), saturation magnetization (Ms) (~354 emu/cm3) and magnetoresistance (MR) (−8.6% under 60 KOe at 300 K) under H ∥ Film plane were obtained for Fe3O4/PMMA heterostructures with a film thickness of 200 nm. The resistivity (ρ), Tv, Ms and MR were hardly affected on several bending tests, proving that Fe3O4/PMMA heterostructures are exciting materials for future flexible spintronics.

Spin valves comprising a synthetic antiferromagnet and a CoFe/Dy/CoFe structure in the pinned layer were prepared by magnetron sputtering. It is shown that the Dy layer is characterized by crystallites, the [0002] direction of which is perpendicular to the film plane; a part of nanostructure, in which the spin-dependent electron scattering occurs, is characterized by smooth interfaces. Variations of magnetotransport properties of the spin valve, which are due to the formation of antiferromagnetic order in the dysprosium layer, are observed. Peculiarities of noncollinear magnetic order of the Dy layer were found to depend on the direction of magnetic moments of adjacent layers and magnetic field strength when passing through the Neel temperature.

The structure and magnetic properties of CoPt–Al2O3 nanocomposite films synthesized by the annealing of Al/(Co3O4 + Pt) bilayers on a MgO(001) substrate at 650°C in vacuum are investigated. The synthesized composite films contain ferromagnetic CoPt grains with an average size of 25–45 nm enclosed in a nonconducting Al2O3 matrix. The saturation magnetization (Ms ~ 330 G) and coercivity (Hc ≈ 6 kOe) of the films are measured in the film plane and perpendicular to it. The obtained films are characterized by a spatial rotational magnetic anisotropy, which makes it possible to arbitrarily set the easy magnetization axis in the film plane or perpendicular to it using a magnetic field stronger than the coercivity (H > Hc).

(Bi1−xLax)(Fe,Co)O3 multiferroic magnetic film were fabricated using pulsed DC (direct current) sputtering technique and demonstrated magnetization reversal by applied electric field. The fabricated (Bi0.41La0.59)(Fe0.75Co0.25)O3 films exhibited hysteresis curves of both ferromagnetic and ferroelectric behavior. The saturated magnetization (Ms) of the multiferroic film was about 70 emu/cm3. The squareness (S) (= remanent magnetization (Mr)/Ms) and coercivity (Hc) of perpendicular to film plane are 0.64 and 4.2 kOe which are larger compared with films in parallel to film plane of 0.5 and 2.5 kOe. The electric and magnetic domain structures of the (Bi0.41La0.59)(Fe0.75Co0.25)O3 film analyzed by electric force microscopy (EFM) and magnetic force microscopy (MFM) were clearly induced with submicron scale by applying a local electric field. This magnetization reversal indicates the future realization of high performance magnetic device with low power consumption.

Poly(ʟ-lactide) (PLLA) films, even of high thickness, exhibiting co-crystalline and crystalline α phases with their chain axes preferentially perpendicular to the film plane (c⊥ orientation) have been obtained. This c⊥ orientation, unprecedented for PLLA films, can be achieved by the crystallization of amorphous films as induced by low-temperature sorption of molecules being suitable as guests of PLLA co-crystalline forms, such as N,N-dimethylformamide, cyclopentanone or 1,3-dioxolane. This kind of orientation is shown and quantified by two-dimensional wide-angle X-ray diffraction (2D-WAXD) patterns, as taken with the X-ray beam parallel to the film plane (EDGE patterns), which present all the hk0 arcs centered on the meridian. PLLA α-form films, as obtained by low-temperature guest-induced crystallization, also exhibit high transparency, being not far from those of the starting amorphous films.

For achieving more functionalities of perovskite manganese oxides film, an epitaxial La0.8Sr0.2MnO3 (LSMO) film was deposited on a flexible substrate (mica) by pulsed laser deposition. The film shows a paramagnetic-ferromagnetic (PM-FM) phase transition at 134 K together with metal-insulator transition (MIT) at 149 K. The measurement of hysteresis loop indicates that the easy-magnetization axis lied in film plane. The transport behavior can be fitted well with the small polaron model, giving out the activation energy Ehop = 176.9 meV. Different from the common anisotropic magnetoresistance (AMR) in manganite film, an isotropic magnetoresistance (IMR) effect was observed in LSMO film and the relatively small thickness of LSMO film ( ∼ 50 nm) is a major reason for it. After the cyclic flexural bending for 1.0 × 104 times, we found the magnetic properties of LSMO film were improved. Micromagnetic detection shows that the activation energy for polaron hopping (Ea = 144.7 meV) remarkably decreases by the cyclic flexural bending process. We suggested that the inhomogeneous/incompact part located at the zone of neighbouring domains become uniform and tight after circulating bending, which facilitates the rotation of domains and the polarons hopping so that the magnetic and electronic performance are enhanced.

A numerical study of the ground state of a ferromagnetic finite film has been performed. The film is characterized by the uniaxial easy-plane bulk magnetic anisotropy and easy-axis surface anisotropy. All calculations were performed for films with parameters of ferrite garnets. The ground state of nano-sized rectangular films (nanocolumns) differing in the cross dimensions is calculated using OOMMF three-dimensional micromagnetic simulation software. The electric polarization is calculated for the vortex magnetization distribution for the ground state. It was found that, in the case of surface anisotropy, the polarization vector component of the film, which is perpendicular to the film plane, is nonzero. A change in the electric polarization upon magnetization of film in an external magnetic field is studied. As the magnetic field increases, the polarization module is also shown to increase to certain values of the field and, after that, decreases to zero. As the cross dimensions of film decreases and the surface anisotropy constant increases, the electric polarization of a nanocolumn increases.

Polymer dispersed nematic liquid crystal (PDNLC) films with conical boundary conditions at the LC-polymer interface are considered. The conical surface anchoring with tilt angle 40° initiates forming the axial-bipolar director configuration inside nematic droplets. This droplet structure exhibits the strong scattering of light polarized parallel to the bipolar axis. In the initial state, the bipolar axes in all droplets are oriented randomly, and therefore PDNLC film scatters a light of any polarization. Electric field applied along the film plane orients the bipolar axes unidirectionally in the whole droplet ensemble, that results in its high polarization-dependent transmittance. Such PDNLC films can be used in the electrically controllable linear polarizers characterized by 89% value of the transmittance for the perpendicular polarized light and high extinction ratio 590:1 at the electric field 0.34 V/μm.

The molecular dynamics method with many-body potential of interatomic interaction constructed in the embedded atom model is used to study the thermal characteristics of aluminum and metastable fcc titanium nanofilms with (0 0 1) and (1 1 0) surface orientation. It is shown that in Al films the linear coefficients of thermal expansion are positive in all the directions, except for the area close to the melting temperature. For fcc titanium the linear coefficients of thermal expansion in the film plane are negative in a wide temperature range. With increasing temperature, in Ti films the local vibrational densities of states of the surface atomic layers, polarized along the x , y , z axes, shift to the low-energy part of the spectrum only in those directions where a decrease in the lattice parameters is observed. The changes in the interface areas of Al films occurring with increase in temperature, lead to the growth of anharmonicity and a “softening” of the local vibration spectra near the critical temperature. It is shown that the negative coefficient of linear expansion is an indicator of the simulated system being in metastable state.

Series of iron thin films have been deposited under vacuum, by thermal evaporation, onto monocrystalline Si(100) and Si(111) substrates. The thickness ranges from 13 to 69 nm. The structural properties have been studied by X-ray diffraction technique, working in the θ–2θ mode and with the Kα Cu radiation (λ = 1.54056 A). The films morphologies have been scanned using atomic force microscopy. Most of the films present a flat surface. The static magnetic measurements were performed by means of a vibrating sample magnetometer, with the external magnetic field applied parallel and perpendicular to the surface of the films. All the films are polycrystalline and present well defined Bragg peaks. Most of the films are under stress. The easy magnetization axis lies in the film plane for all the samples. Values of squareness up to 1 have been measured in the longitudinal configuration. In Fe/Si (100), coercivity seems to depend closely on crystallite size. All these results will be presented and discussed.

The Faraday-effect has been used for the measurement of magnetic field induced by electric current. Actually, an optical fiber sensor using the Faraday-effect has been developed as an alternative method of the current-transformer in the substation of the AC electric power system. However, in the optical fiber electric current sensor, it is difficult to minimize the sensor head because the optical fiber must be wound to a conductor wire. Recently, we proposed an optical magnetic field sensor with a small head [1] for the switching current measurement for the SiC/GaN power-devices, which consisted of a Faraday-element using a magnetic thin film. Such a magnetic thin film for the Faraday-element must have both higher transmittance for the light (transparency) and large Faraday-effect. Rare earth substituted yttrium iron garnet film (R:YIG) with high transmittance and large Faraday-effect has been widely studied, and a cerium substituted film (Ce:YIG) with high performance has recently been reported [2]. However, Ce:YIG film has a temperature-dependent magnetization owing to the low Curie temperature around or below 300 deg C. In this study, we focus on a granular film with ferromagnetic fine metal particles dispersed in an insulator matrix to obtain high transmittance and large Faraday-effect. Actually, N. Kobayashi et al. [3] reported a FeCo-AlF granular film with high transmittance. J. L. Dorman et al. [4] also reported a Fe-Al 2 O 3 granular film with large Faraday rotation angle of 3000 to 4000 deg./cm at 1550 nm wavelength. In our study, to develop the Faraday-element for the optical magnetic field sensor, the granular film was fabricated by co-evaporation method using cobalt (Co) and magnesium fluoride (MgF 2 ). The evaporation rate ratio was kept to Co: MgF 2 = 1: 2 (Co volume fraction of 0.33). The substrate- temperature during co-evaporation was R.T. to 450 deg C. The magnetic and magneto-optical properties of the film were characterized. The substrate-temperature dependences of the cobalt particle diameter and the extinction coefficient k in the Co-MgF 2 granular film deposited by co-evaporation are shown in Fig. 1. The Co particle diameter became large proportional to the substrate-temperature during the deposition. At low substrate-temperature during the deposition, average Co-granule diameter was about 3 nm and the granular film exhibited a superparamagnetism. On the other hand, not shown here in detail, at the substrate-temperature during the deposition of 350 deg C or above, the granular film exhibited a magnetization curve with a hysteresis as an evidence of the ferromagnetic behaviour. O. Kitakami et al. [5] reported a superparamagnetic critical diameter of hcp-Co, it was estimated to be about 7 nm, in our study, such the critical Co diameter was estimated to be about 4 nm. The cobalt particle size became large and the k of the film became low with increasing the substrate-temperature during the deposition. The minimum k of the film was 0.028 at the substrate-temperature of 450 deg C, which was much smaller than those of previous studies. Even in constant concentration of Co or MgF 2 in the film, the k changed by substrate-temperature during the deposition. We considered that the distance between the adjacent cobalt particles became wider when the cobalt particle became larger, and such a relationship between cobalt particle size and the distance between the adjacent particles was considered to be strongly related to the low k of the Co-MgF 2 granular film. Fig. 2 shows the magnetization curve of Co-MgF 2 granular film deposited at 350 deg C measured in the film plane and perpendicular to the film plane, and the Faraday-rotation angle versus applied magnetic field. From Fig. 2, the Co-MgF 2 granular film had the in-plane aligned magnetization, and the perpendicular magnetization process was considered to be due to the magnetization rotation by the perpendicular demagnetizing effect. Although not shown here, even at ambient temperature of 350 deg C, the decrease of saturation magnetization M s of the Co-MgF 2 granular film deposited at 350 deg C was a little 10 %. Therefore, the Co-MgF 2 granular film was considered to have a Curie temperature much higher than 350 deg C. In Fig. 2, the Faraday-rotation loop was corresponding to the magnetization curve well. The Faraday-rotation angle was linearly proportional to the applied magnetic field within ±2 kOe.

The effects of the partial substitution of Mn by Co/Fe on the structural, magnetostatic, and magnetodynamic properties of Ni–Mn–In Heusler alloy films were studied using X-ray diffraction, field-dependent magnetization, and ferromagnetic resonance studies. It was observed that the substitution of up to 3 at.% Co or Fe atoms in Mn sites does not alter the crystal structure much. However, an increase in grain size and surface roughness was noticed upon substitution of the fourth element. The magnetic moment of the films could be increased up to 120 kA/m by introducing Co/Fe in Mn sites. For the first time, low Gilbert damping constant ( $\alpha$ ) of 0.008 is observed in Co substituted Ni–Mn–In film together with high saturation magnetization, high perpendicular anisotropy, and an easy axis along film plane, which are the promising factors for application in high-density random-access memory devices.

We have studied current induced magnetization switching in W/CoFeB/MgO based three terminal magnetic tunnel junctions. The switching driven by spin—orbit torque (SOT) is evaluated in the so-called type-Y structure, in which the magnetic easy-axis of the CoFeB layer lies in the film plane and is orthogonal to the current flow. The effective spin Hall angle estimated from the bias field dependence of critical current (Ic) is ~ 0.07. The field and current dependence of the switching probability are studied. The field and DC current induced switching can be described using a model based on thermally assisted magnetization switching. In contrast, the 50 ns long pulse current dependence of the switching probability shows significant deviation from the model, even if contribution from the field-like torque is included. The deviation is particularly evident when the threshold switching current is larger. These results show that conventional thermally assisted magnetization switching model cannot be used to describe SOT induced switching using short current pulses.

We demonstrate a new structural optimization of cobalt–(barium fluoride) lateral nanogranular films, achieving independently variable direct current (DC) and alternating current (AC) tunneling effects, in the film plane and out of the plane, respectively. Lateral nanogranular films were successfully fabricated via programmable tandem sputtering. Flat-shaped magnetic Co nanogranules were periodically inserted between dielectric barium fluoride layers of different thicknesses. All the lateral nanogranular films were insulating, with electrical resistivities ρ exceeding 1013 μΩ·cm, even with a Co content as high as 30 at.%. A lateral tunneling magnetoresistance (TMR) effect and vertical tunneling magnetodielectric (TMD) effect were found in the same lateral nanogranular film with 30 at.% Co. For a nanogranular film with lateral Co nanoparticles, the sensitivity of both the TMR and TMD ratio were improved at small magnetic fields compared with conventional films with spherical Co nanoparticles, reflecting its small saturation magnetic field. This layer-ordered metal–insulator nanogranular structure has potential applications in AC/DC hybrid elements as a high-sensitivity magnetic sensor.

Recently, nanolaminated ternary carbides have attracted immense interest due to the concomitant presence of both ceramic and metallic properties. Here, we grow nanolaminate ${\mathrm{Ti}}_{3}{\mathrm{Al}\mathrm{C}}_{2}$ thin films by pulsed laser deposition on c-axis-oriented sapphire substrates and, surprisingly, the films are found to be highly oriented along the (103) axis normal to the film plane, rather than the (000l) orientation. Multiple characterization techniques are employed to explore the structural and chemical quality of these films, the electrical and optical properties, and the device functionalities. The 80-nm thick ${\mathrm{Ti}}_{3}{\mathrm{Al}\mathrm{C}}_{2}$ film is highly conducting at room temperature, with a resistivity of about 50 \textmu{}\ensuremath{\Omega} cm and a very-low-temperature coefficient of resistivity. The ultrathin (2 nm) ${\mathrm{Ti}}_{3}{\mathrm{Al}\mathrm{C}}_{2}$ film has fairly good optical transparency (\ensuremath{\sim}70%) and high conductivity (sheet resistance \ensuremath{\sim}735 \ensuremath{\Omega}/sq) at room temperature. Scanning tunneling microscopy reveals the metallic characteristics (finite density of states at the Fermi level) at room temperature. The metal-semiconductor junction of the p-type ${\mathrm{Ti}}_{3}{\mathrm{Al}\mathrm{C}}_{2}$ film and n-$\mathrm{Si}$ show the expected rectification (diode) characteristics, in contrast to the ohmic contact behavior in the case of ${\mathrm{Ti}}_{3}{\mathrm{Al}\mathrm{C}}_{2}/$p-$\mathrm{Si}$. A triboelectric-nanogenerator-based touch-sensing device, comprising of the ${\mathrm{Ti}}_{3}{\mathrm{Al}\mathrm{C}}_{2}$ film, shows a very impressive peak-to-peak open-circuit output voltage (\ensuremath{\sim}80 V). These observations reveal that pulsed laser deposited ${\mathrm{Ti}}_{3}{\mathrm{Al}\mathrm{C}}_{2}$ thin films have excellent potential for applications in multiple domains, such as bottom electrodes, resistors for high-precision measurements, Schottky diodes, ohmic contacts, fairly transparent ultrathin conductors, and next-generation biomechanical touch sensors for energy harvesting.

We report results of galvanomagnetic and terahertz time-domain spectroscopy measurements on thin films of Bi 1 &minus, x Sb x on polyimide and mica substrates with various antimony concentrations (x from 0 to 15 %) and film thickness (70, 150 nm). The resistivity, Hall coefficient and magnetoresistivity of the films were measured experimentally in the magnetic field of 0.65 T at room temperature. Mobility and concentration of electrons and holes in the film plane were calculated using the transport coefficients. The terahertz time-domain spectroscopy is used to measure the complex conductivity and permittivity of Bi 1 &minus, x Sb x thin films on the dielectric substrates in the frequency range from 0.2 to 1 THz. The plasma frequency, relaxation time, DC conductivity and effective carrier mass were extracted from these data and evaluated as functions of the Sb concentration for different film thickness and substrate. We observed that the film magnetoresistivity decreases with increasing the Sb concentration and for most of the films the Hall coefficient is negative and depends on the external factors insignificantly. We show that the mobility of charge carriers weakly depends on Sb concentration, which confirms the assertion about the scattering of carriers on themselves and not on defects in the structure. It was revealed that film static and dynamic resistivity (conductivity) as well as dielectric permittivity depend on Sb content and the film thickness. The results may be used for development of various thermoelectric, electronic and optical devices, such as THz detectors or components which can control the properties of THz radiation.

Funding: UK EPSRC (GR/S62628/01) and Royal Society Wolfson Research Merit Award (I.D.W.S.). We have used absorption, photoluminescence (PL) and variable angle spectroscopic ellipsometry (VASE) measurements to investigate the structural changes that take place upon high temperature annealing in spin-coated films of the prototypical conjugated polymer (CP) poly[2-(2’-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene] (MEH-PPV). Absorption and VASE measurements reveal that the birefringence of the films increases by approximately a factor of two upon heating, which indicates significant increase in the alignment of the conjugated polymer (CP) strands within the film plane. Absorption and PL spectra indicate the formation in annealed films of interchain species having lower energy transitions. But these measurements alone do not reveal the type of interchain species formed, such as excimers or aggregates. VASE measurements were used to investigate this feature and clearly reveal a new, low energy, feature with a shoulder at 650 nm in the dispersion relations of the extraordinary (out-of-plane) extinction and absorption coefficients of annealed films, which we assign to aggregate absorption. Thus, our work shows that VASE is a sensitive enough technique to measure aggregate absorption in CP films. In the case of the ordinary (in-plane) extinction and absorption coefficients, there is increased amplitude of the lower energy peak upon heating, owing to increased uniaxial anisotropy, along with a broadening and a longer red-tail, but the well-resolved red-shifted absorption band seen for the extraordinary absorption coefficient, is not observed. Therefore, we conclude that while in-plane and out-of-plane aggregation occurs in annealed spin-coated films of MEH-PPV, aggregate absorption is only clearly observed when the aggregate electronic transition dipole is oriented preferentially in a direction perpendicular to the film plane. This conclusion is consistent with the usual observation that aggregate absorption in MEH-PPV films is not easily observed using absorption spectra alone, which are typically measured at normal incidence. Postprint

In the present study, we demonstrate the measurement of resistivity tensor ($\rho$) along the magnetic axes of a polycrystalline film of ferromagnetic permalloy (Py). To this end, conventional Hall-bar and a more recent extended van der Pauw methods were utilized for determining 2D $\rho$ in the film plane. The samples were prepared by normal incidence sputter deposition within an in-situ magnetic field to induce in-plane uniaxial magnetic anisotropy in the film. Since $\rho$ might be affected by the internal magnetization of the film, we performed measurements by rotation of a saturating magnetic field in the film plane. Both methods indicate that the average resistivity is lower along the easy axis of the film compared to the hard axis. Since X-ray diffraction results indicated no dominating texture in the film, we concluded that there is a correlation between uniaxial magnetic axes and principal resistivity axes. This is an important finding that allows determining the direction of magnetic anisotropy axes without magnetometry. The results also verify atomic or pair ordering to be the origin of uniaxial magnetic anisotropy in the Py since resistivity is sensitive to the level of order in solids. The extended van der Pauw utilized here can be easily performed on the as-received samples which is of practical interest., Comment: 5 pages, 5 figures

We present deposition and characterization of multilayers consisting of 20 repetitions of 15 $\r{A}$ thick permalloy Ni$_{80}$Fe$_{20}$ at. \% (Py) and 5 $\r{A}$ Pt. The samples were prepared by two different sputter deposition methods, namely dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS), that represent low and moderate ionized flux fraction of the film forming material, respectively, for deposition of the Py layers. The effect of substrate roughness, working gas pressure and sputter power on the in-plane uniaxial magnetic anisotropy of the films are studied. The multilayers were characterized by X-ray reflectivity and diffraction, and by magneto-optical Kerr effect (MOKE). It is shown that HiPIMS deposition produces multilayers with unique surface roughness regardless of the substrate surface roughness. Multilayers prepared by both dcMS and HiPIMS deposition present a strong (111) texture normal to the film plane. The results show that utilizing HiPIMS for deposition of the Py layer leads to a minimum interface mixing between individual layers compared to dcMS deposition performed at sputter power. This is associated with the smooth surface of Py deposited by HiPIMS. However, this sharp interface results in higher coercivity and an opening in the hard axis hysteresis loops while multilayers with intermixing present well defined in-plane uniaxial anisotropy i.e. a linear hard axis. Comparison with Py/Cu and Py/CuPt multilayers, prepared under identical conditions using HiPIMS, suggests that poor in-plane uniaxial anisotropy is obtained in the Py/Pt case, caused by the inverse magnetostriction arising from the large lattice mismatch between Py and Pt. The Py/Pt multilayers that exhibit interface mixing have a more relaxed interface and thus presents negligible inverse magnetostriction and have better defined anisotropy., Comment: 7 pages, 5 figures

Ferromagnetic thin films with moderate perpendicular magnetic anisotropy (PMA) are known to support weak stripe domains provided film thickness exceeds a critical value. In this work, we performed both an experimental and theoretical investigation of a peculiar phenomenon shown by weak stripe domains: namely, the stripe domains reorientation when a dc magnetic field is applied in the film plane along the direction perpendicular to the stripes axis. We focus on bct α′-Fe8N1−x thin films obtained by N 2 + implantation of α-Fe films epitaxially grown on ZnSe/GaAs(001). By using different ion implantation and heat treatment conditions, we show that it is possible to tune the PMA values. Magnetic force microscopy and vibrating sample magnetometer measurements prove the existence of weak stripe domains at remanence, and of a threshold field for the reorientation of the stripes axis in a transversal field. Using a one-dimensional model of the magnetic stripe domains, where the essential parameter is the maximum canting angle of the stripe magnetization out of the film plane, the various contributions to the magnetic energy can be separately calculated. A linear increase of the reorientation threshold field on the PMA is obtained, in qualitative agreement with experimental data in our Fe–N films, as well as in other thin films with weak stripe domains. Finally, we find that also the rotatable anisotropy field linearly increases as a function of the PMA magnitude.

The evolution of electric field assisted dissolution (EFAD) of nanoparticles process is studied by means of spectroscopic ellipsometry. Multilayer structures with embedded Ag islands films are prepared by electron beam evaporation and subjected to EFAD process using different voltages and treatment times. Modelling of ellipsometric data evidences the dissolution process by the progressive quenching of the localized surface plasmon resonance of nanoparticles. Further quantitative information is revealed by the analysis of the effective dielectric function of Ag islands films in terms of the spectral density function. The amount of dissolved metal appears to follow a non-linear dependence with the applied voltage. Ag islands become elongated in the film plane as dissolution takes place. In the case of multiple Ag islands films, the process occurs in a sequential way, starting from the film closest to the glass substrate. Accumulation of Ag in a near-surface glass region is revealed by the presence of a refractive index gradient. Overall, the study demonstrates the usefulness of ellipsometry for providing novel insights into the EFAD process.

The local atomic structure and the magnetic response of Co films intercalated between Graphene and Ir(111) were investigated combining polarized X-ray Absorption Spectroscopy at the Co K edge with Magneto-Optic Kerr Effect. The structural and magnetic evolution upon a 500 ° C annealing was evaluated as a function of the film thickness. After the thermal treatment, our thick film (10 monolayers) presented a lower perpendicular magnetic anisotropy (PMA) as well as a reduced average structural disorder. On the other hand, in our thin film (5 monolayers), the annealing enhanced the perpendicular magnetic response and induced a local anisotropy by stretching the Co-Co bonds in the film plane and compressing those outside the plane. Our finding emphasizes the close relationship between the local structure of Co within the film and its magnetic properties.

We report the fabrication and characterization of Ba3Zn2Fe24O41 (Zn2Z) hexaferrite films on silicon substrates using a simple sol-gel drop casting method. A combination of X-ray diffraction (XRD), scanning electron microscope (SEM), grazing incidence wide angle X-ray scattering (GIWAXS) and vibrating sample magnetometer (VSM) was used to characterize the structural and magnetic properties of the films. The XRD results confirmed the formation of the Z-type hexaferrite with some ZnFe2O4 and α-Fe2O3 phases. SEM images showed several micron-size platelet-like hexagonal crystals with nanocrystals grown onto their surfaces. Interestingly, a few regions of the film exhibit self-assembly of the nanocrystals in ordered patterns. GIWAXS measurements indicated that the crystals are not randomly oriented within the film. The magnetic results revealed typical characteristics of a soft magnetic material consistent with the Z-type characteristics. The magnetization did not reach saturation up to the maximum applied field of 6 kOe. The saturation magnetization obtained with the field applied perpendicular to the film plane was found to be lower than that for a parallel geometry.

Finite element simulations for detecting the dielectric permittivity of planar nanoscale dielectrics by electrostatic probe are performed to explore the microprobe technology of characterizing nanomaterials. The electrostatic force produced by the polarization of nanoscale dielectrics is analyzed by a capacitance gradient between the probe and nano-sample in an electrostatic detection system, in which sample thickness is varied in the range of 1 nm&ndash, 10 &mu, m, the width (diameter) encompasses from 100 nm to 10 &mu, m, the tilt angle of probe alters between 0&deg, and 20&deg, and the relative dielectric constant covers 2&ndash, 1000 to represent a majority of dielectric materials. For dielectric thin films with infinite lateral dimension, the critical diameter is determined, not only by the geometric shape and tilt angle of detecting probe, but also by the thickness of the tested nanofilm. Meanwhile, for the thickness greater than 100 nm, the critical diameter is almost independent on the probe geometry while being primarily dominated by the thickness and dielectric permittivity of nanomaterials, which approximately complies a variation as exponential functions. For nanofilms with a plane size which can be regarded as infinite, a pertaining analytical formalism is established and verified for the film thickness in an ultrathin limit of 10&ndash, 100 nm, with the probe axis being perpendicular and tilt to film plane, respectively. The present research suggests a general testing scheme for characterizing flat, nanoscale, dielectric materials on metal substrates by means of electrostatic microscopy, which can realize an accurate quantitative analysis of dielectric permittivity.

We investigated the spin-dependent transport properties of a lateral spin-valve device with a 600 nm-long GaAs channel and ferromagnetic MnGa electrodes with perpendicular magnetization. Its current-voltage characteristics show nonlinear behavior below 50 K, indicating that tunnel transport through the MnGa/GaAs Schottky barrier is dominant at low temperatures. We observed clear magnetoresistance (MR) ratio up to 12% at 4 K when applying a magnetic field perpendicular to the film plane. Furthermore, a large spin-dependent output voltage of 33 mV is obtained. These values are the highest in lateral ferromagnetic metal / semiconductor / ferromagnetic metal spin-valve devices reported so far.

Ferromagnetism and magnetic anisotropy in Mn–Al thin films can be of great interest due to their applications in spintronic components and as rare-earth free magnets. Temperature-dependent uniaxial anisotropy has been observed in ferromagnetic MnAl thin films, which is attributed to the modification of the tetragonal lattice distortion with the change in annealing temperature, confirmed by VSM, MOKE and XRD results; the annealing time did not affect the magnetic anisotropy. A simple evaporation technique was used to deposit the Mn/Al bilayer thin films (thickness ∼ 64 nm) on GaAs substrates. A comprehensive study of the effect of annealing temperature as well as annealing time on structural, microstructural, magnetic and magneto-optical properties are reported in this paper. The ferromagnetic phase was enriched in annealed samples, which was confirmed by XRD, MOKE and magnetic hysteresis loops. XRD results revealed that the ferromagnetic τ-phase was enhanced in annealed films with the increase in annealing temperature ≥ 400 °C. Surface roughness was estimated from the AFM micrographs and was found to be increased, whereas the mean grain size was decreased on annealing the as-deposited Mn/Al bilayer thin film. The gradual increase in magnetic coercivity was found on increasing the annealing temperature. It is interesting to note that the magnetic easy axis can be tuned by changing the annealing temperature of MnAl thin films, and the easy axis changes from perpendicular to parallel direction of the film plane when the annealing temperature varies from 400 °C to 500 °C. MOKE results were also found to be consistent with the magnetic results.

Magnetic force microscopy (MFM) has been used to probe the influence of an in situ applied in-plane elastic strains and/or magnetic field on the static magnetic configuration of a 530 nm magnetostrictive FeCuNbSiB thin film. The film shows a typical magnetic stripe domain configuration with 180 nm magnetic domain width presenting its magnetic moments oriented perpendicularly to the film plane. The in-plane strain was induced via the application of a voltage in a piezoelectric (PE) actuator on which the film/substrate system was glued. The FeCuNbSiB film was deposited onto a compliant polyimide substrate (Kapton) in order to avoid clamping effects that can lead to low transmission of strains from the actuator to the film/substrate system. The instrumental setup was modified with a custom-built electromagnet for performing in situ MFM experiments under the application of an in-plane magnetic field. We could compare the strain-mediated effect upon the magnetic domain configuration with the effect of an applied magnetic field. This paper clearly shows a better-defined electric field/strain control of the local domain magnetization (size and orientation). The efficient coupling between the magnetostrictive properties of the FeCuNbSiB film and the PE ones of the actuators allows a complete switching of the out-of-plane domain magnetization toward an in-plane homogeneous magnetic one. This magnetoelectric heterostructure can thus open the way for new devices allowing the electric control of the magnetic information at the nanoscale level.

In this study, we examined the effect of Si-ion irradiation on Rs of YBCO thin films. We measured Rs 90 and Rs0 of YBCO thin films in a magnetic field applied both normal and parallel to the film plane. Si-ion irradiation conditions were configured as follows: irradiation energy = 50–500 keV, irradiation ion density = 1–8 × 10 12 ion/ cm2. We found that the Rs90 decreased through ion irradiation, and Si-ion irradiation with an irradiation energy of 200 keV and an irradiated ion density of 4 × 1012 ion/cm2 being the most effective configuration for reducing Rs90 in high magnetic fields. Magnetic field-dependent Rs0 was quite small for all YBCO films with and without ion irradiation. When a magnetic field is applied parallel to the film plane, the blocking layers of the YBCO act as strong pins, therefore, R s0 in the magnetic field is small without introduction of artificial pins. However, we found that the Rs0 of YBCO films became small with Si-ion irradiation than that of the YBCO film without Si-ion irradiation, that the condition of ion energy 200 keV and ion irradiation density 1 × 10 12 ion/cm2 could reduce Rs0 most.

Martensitic transformation (MT) and magnetic properties were investigated in a polycrystalline Ni-Mn-Ga freestanding and a sputter deposited on Al2O3 substrate films with excess Ni and Ga. Both films had a 2-μm thickness and MT above the room temperature. The MT region was wider in the freestanding film. The films demonstrated the isotropic in-plane behaviour of magnetic properties. A step-like behaviour was observed in the magnetization reversal process in the freestanding film because there were second-phase impurities. In the substrate-constrained film, only broadening in magnetization loops because of internal stresses was observed. The easy magnetization axis oriented normally to the film plane of the freestanding film but had a preferred orientation in the film plane of the substrate-constrained film. Both films exhibited a maze-like surface magnetic domain structure with the domain width of approximately 0.9 μm with different stripe structures, which confirms the presence of out-of-plane anisotropy. Based on these results, the effects of the substrate on the MT, structural and magnetic properties and the type of internal stresses were discussed.

The synthesis and characterization of thin M-type barium hexaferrite (BaFe12O19 or BaM) films on silicon are reported. Multilayer in situ technique was employed to anneal the films at 850–900 °C for 10 min. The thickness dependence of the magnetic properties of the BaM films has been investigated using VSM. For the BaM 150 nm thickness film, acicular BaM grains were present having their c-axis randomly oriented. For the BaM films thicker than 150 nm, lattice relaxation favors the c-axis to be aligned in the film plane. The micromagnetic simulation was used to model the out-of-plane and the in-plane hysteresis loops. We have achieved good matching between the experimental data and the model. Using the micromagnetic model, we have estimated the deflection angle of c-axis from the normal plane θ = 25° for the 150 nm thick film. Keywords: Barium hexaferrite, Magnetic properties, Hysteresis loop, Micromagnetic modeling, VSM

Current induced spin wave excitations in spin transfer torque nano-contacts are known as a promising way to generate exchange-dominated spin waves at the nano-scale. It has been shown that when these systems are magnetized in the film plane, broken spatial symmetry of the field around the nano-contact induced by the Oersted field opens the possibility for spin wave mode co-existence including a non-linear self-localized spin-wave bullet and a propagating mode. By means of micromagnetic simulations, here we show that in systems with strong perpendicular magnetic anisotropy (PMA) in the free layer, two propagating spin wave modes with different frequency and spatial distribution can be excited simultaneously. Our results indicate that in-plane magnetized spin transfer nano-contacts in PMA materials do not host a solitonic self-localized spin-wave bullet, which is different from previous studies for systems with in plane magnetic anisotropy. This feature renders them interesting for nano-scale magnonic waveguides and crystals since magnon transport can be configured by tuning the applied current., Comment: 6 pages, 3 figures

The extraordinary ability of poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) dense films, exhibiting a nanoporous-crystalline (NC) phase, to absorb traces of organic pollutants dissolved in water is shown. Equilibrium uptakes and sorption kinetics of perchloroethylene (PCE) are much higher and faster than for the corresponding amorphous films. For sorption kinetics, particularly relevant is a control of the planar orientation of the NC phase. For instance, for PCE sorption from 50 ppm aqueous solutions, a NC α form film with orientation of the crystalline polymer chains being preferentially perpendicular to the film plane (c⊥ orientation) exhibit a diffusivity nearly 14 times higher than for a NC film with crystalline polymer chains being preferentially parallel to the film plane (c// orientation) and nearly 88 times higher than for the starting amorphous PPO film. This phenomenon is rationalized in terms of crystalline channels being preferentially perpendicular to the film plane. Moreover, equilibrium uptakes for NC PPO films are much higher than for NC sPS films. For instance, for sorption experiments from PCE 50 ppm aqueous solutions, equilibrium uptakes for NC PPO and sPS films are nearly 15 wt% and 2 wt%, respectively. This phenomenon is rationalized by the high-free volume of both NC and amorphous phases of PPO.

Giant magnetoresistance (GMR) behavior in electrodeposited NiFe/Cu multilayers was investigated as a function of non-magnetic (Cu) and ferromagnetic (NiFe) layer thicknesses, respectively. Prior to the GMR analysis, structural and magnetic analyses of the multilayers were also studied. The elemental analysis of the multilayers indicated that the Cu and Ni content in the multilayers increase with increasing Cu and NiFe layer thickness, respectively. The structural studies by X-ray diffraction revealed that all multilayers have face centred cubic structure with preferred (1 1 0) crystal orientation as their substrates. The magnetic properties studied with the vibrating sample magnetometer showed that the magnetizations of the samples are significantly affected by the layer thicknesses. Saturation magnetisation, M-s increases from 45 to 225 emu/cm(3) with increasing NiFe layer thickness. The increase in the Ni content of the multilayers with a small Fe content causes an increase in the Ms. And, the coercivities ranging from 2 to 24 Oe are between the soft and hard magnetic properties. Also, the magnetic easy axis of the multilayers was found to be in the film plane. Magnetoresistance measurements showed that all multilayers exhibited the GMR behavior. The GMR magnitude increases with increasing Cu layer thickness and reaches its maximum value of 10% at the Cu layer thickness of 1 nm, then it decreases. And similarly, the GMR magnitude increases and reaches highest value of pure GMR (10%) for the NiFe layer thickness of 3 nm, and beyond this point GMR decreases with increasing NiFe layer thickness. Some small component of the anisotropic magnetoresistance was also observed at thin Cu and thick NiFe layer thicknesses. It is seen that the highest GMR values up to 10% were obtained in electrodeposited NiFe/Cu multilayers up to now. The structural, magnetic and magnetoresistance properties of the NiFe/Cu were reported via the variations of the thicknesses of Cu and NiFe layers with stressing the role of layer thicknesses on the high GMR behavior. Türkiye Cumhuriyeti Kalkınma Bakanlığı - 2005K120170 Balıkesir Üniversitesi - BAP 2001/02 - 2005/38 - BAP 2006/37 DPT -- 2005/38, 2005K120170, BAP 2001/02

Crystallographically aligned nanocrystalline films of the ferromagnetic spinel CuCr 2 Se 4 were successfully synthesized and their structure and alignment were confirmed by X-ray diffraction and high-resolution transmission electron microscopy. The average size of the crystallites is about 200–250 nm, and their (1 1 1) crystal planes are parallel to the film plane. A good match of the film’s electronic structure to that of bulk CuCr 2 Se 4 is confirmed by transverse Kerr effect measurements. Four easy 〈1 1 1〉 axes are present in the films. One of these axes is oriented perpendicular and three others are oriented at an angle of 19.5° relative to the film plane. The magnetic properties of the films are determined by a competition between the out-of-plane magnetocrystalline anisotropy and the in-plane shape anisotropy. Magnetic measurements show that the dominating type of anisotropy switches from shape to magnetocrystalline anisotropy near 160 K, which leads to a switch of the effective easy axis from inside the film plane at room temperature to perpendicular to the film plane as the temperature decreases. At last, a moderately large, negative value of the low-temperature magnetoresistance was observed for the first time in CuCr 2 Se 4 films.

Structure of amorphous nangranular composite (Co86Nb12Ta2) x (SiO2)1−x films was studied by means of grazing-incidence small-angle X-ray scattering as a function of atomic concentration x of the metal fraction in vicinity of the percolation threshold. It has been established that the average size of magnetic nanoparticles increases with x and this increment exhibit the anisotropic character. It was found that in a whole concentration range the particles are elongated along the growth direction perpendicular to the film plane. For the lowest concentration x = 0.193, clusters with isotropic shape and average radius of 1 nm were observed, while for higher concentrations up to x = 0.665, the average cluster length along the film normal is 1.5–7 nm and the cross-section is 1–2 nm.

This report is on strain control of magnetic order parameters in 50 nm epitaxial NiFe2O4 (NFO) films grown on (001), (110), and (111) SrTiO3 (STO) single-crystal substrates by pulsed laser deposition. The related in-plane strains for NFO films on (001), (110), and (111) STO substrates are found to be ―1.36 %, 1.35 %, and 1.52 %, respectively, where the lattice mismatch between film and substrate is as high as 6.7 %. Our analysis of magnetization and ferromagnetic resonance on all the NFO films reveals the presence of a uniaxial anisotropy field, which is perpendicular to the film plane. The anisotropy field decreases with the increase of strain in NFO films. Specifically, NFO films on STO (111) and STO (001) have the lowest and highest uniaxial anisotropy fileds of 1.4 kOe and 6.1 kOe, respectively. These experimental values of anisotropy field are a factor of 5–10 times smaller than those of the calculated ones due to the film defects induced by the high lattice mismatch. The studies of magnetic anisotropy of spinel ferrite films are of interest for spintronics and microwave devices.

Low temperature annealing effect on the structure, residual stress and local chemical order of Ni2MnGa alloys thin films were investigated by atomic force microscopy, x-ray diffraction and x-ray stress analyses as well as extended x-ray absorption fine structure. Thin films were prepared by sputtering on GaAs substrates maintained at room temperature and 300 °C during deposition. The samples prepared at 300 °C were subsequently annealed at 150 °C and 300 °C for one and half hour. X-ray diffraction measurements indicated both a development of crystalline texture in which austenite (110) crystalline planes are preferentially aligned parallel to the film plane as well as compressive residual stress, mainly induced by the accommodation of the film on the substrate surface and by heating-cooling in the growth process. Atomic force microscopy analyses reveal a surface morphology dominated by a topography of hillocks and peaked massifs, whose roughness increases by about twenty times with the increase in the crystalline texture induced by annealing at 300 °C of the samples. Interestingly, extended x-ray absorption fine structure analysis performed at Mn K-edge indicate that residual stress is preserved even after significant increase of the structural and chemical ordering induced by the low temperature annealing.

Development of ultra-sensitive mechanical pressure sensors is required for various technological fields such as medical diagnosis and gas leakage. Aluminum nitride (AlN) thin films deposited by rf reactive sputtering on flexible aluminum substrates show a piezoelectric response to an ultra-small mechanical pressure in the scale of few Pa. This result is achieved only in the case where the residual average stress in the AlN film is close to zero. The deposition temperature determines the crystallographic orientation of the grains relative to the AlN film plane and consequently the type and magnitude of the residual stress in the film. Various sources of mechanical pressures were applied on the AlN films including a stream of air from a narrow diameter nozzle, sound waves in air and a piezoelectric actuator. In addition, a thermally induced pressure was tested. The scale of the applied mechanical pressures was calibrated and found to be in the range of few Pascals. The piezoelectric response of the AlN film is correlated with the mismatch of atomic arrangement at the AlN film/Al substrate interface.

The nanoscale distribution of Bi in InPBi is determined by atom probe tomography and transmission electron microscopy. The distribution of Bi atoms is not uniform both along the growth direction and within the film plane. A statistically high Bi-content region is observed at the bottom of the InPBi layer close to the InPBi/InP interface. Bi-rich V-shaped walls on the (−111) and (1–11) planes close to the InPBi/InP interface and quasi-periodic Bi-rich nanowalls in the (1–10) plane with a periodicity of about 100 nm are observed. A growth model is proposed to explain the formation of these unique Bi-related nanoscale features. These features can significantly affect the deep levels of the InPBi epilayer. The regions in the InPBi layer with or without these Bi-related nanostructures exhibit different optical properties.

Ray tracing is used to find improved set-ups of the projector system of a JEOL ARM 200CF TEM/STEM for use in coupling it to a Gatan 965 Quantum ER EELS system and to explain their performance. The system has a probe aberration corrector but no image corrector. With the latter, the problem would be more challenging. The agreement between the calculated performance and that found experimentally is excellent. At 200kV and using the 2.5mm Quantum entrance aperture, the energy range over which the collection angle changes by a maximum of 5% from that at zero loss has been increased from 1.2keV to 4.7keV. At lower accelerating voltages, these energy ranges are lower e.g. at 80kV they are 0.5keV and 2.0keV respectively. The key factors giving the improvement are an increase in the energy-loss at which the projector cross-over goes to infinity and a reduction of the combination aberrations that occur in a lens stack. As well as improving the energy-loss range, the new set-ups reduce spectrum artefacts and minimise the motion of the diffraction pattern at low STEM magnification for electrons that have lost energy. Even if making the pivot points conjugate with the film plane gives no motion for zero-loss electrons, there will be motion for those electrons that have lost energy, leading to a false sense of security when performing spectrum imaging at low magnifications. De-scanning of the probe after the objective lens is a better way of dealing with this problem.

Magnetic properties and high frequency characteristics of (Fe70.6Co29.4)100−xZrx (x = 4.0 − 18.2 at.%) thin films have been investigated. The saturation magnetization 4πM s decreases continuously from 21.7 kGs for x = 4.0 at.% to 12.2 kGs for x = 18.2 at.% and it is consistent with the decreasing of Fe-Co composition. It is found that the films show nearly isotropic magnetic behavior in the film plane for the Zr content ranging from 7.2 to 18.2 at.%. These films exhibit a weak perpendicular magnetic anisotropy with coercivity values of 24–67 Oe. Meanwhile, the in-plane isotropic FeCoZr films show a good high frequency response of permeability. In particular, the film with x = 7.2 at.% shows a resonance frequency of 2.8 GHz along the direction perpendicular to the stripe domain axis. The permeability spectra of the thin films with higher Zr content display multiple resonance peaks, which may be due to the perpendicular magnetic anisotropy induced by the stress.

Oriented barium hexaferrite films grown on wide band-gap semiconductor substrates (such as SiC) are promising candidates for high-power microwave integrated devices. In this work, BaFe 12 O 19 (BaM) films with c -axis randomly distributed in the film plane were prepared by direct current magnetron sputtering on a -plane 6H-SiC substrates. An insight into the orientation relationship and the epitaxial-like growth mechanism demonstrates that ( 11 2 ¯ 0 ) planes of BaM have been grown on ( 11 2 ¯ 0 ) 6H-SiC substrates. The random alignment of [0001] axis within the film plane was revealed by X-ray diffractions, X-ray pole figures, polarized Raman spectra and magnetic hysteresis loops. The BaM films on 6H-SiC substrates exhibited a large remanence ratio, M r / M s , of about 0.64 along in-plane axis and a relatively small one of ~0.2 for the out-of-plane hard axis, showing the potential of application in self-biased microwave devises.

Epitaxial thin films of CoFe2O4 (CFO) have successfully been transferred from a SrTiO3 substrate onto a flexible polyimide substrate. By bending the flexible polyimide, different levels of uniaxial strain are continuously introduced into the CFO epitaxial thin films. Unlike traditional epitaxial strain induced by substrates, the strain from bending will not suffer from critical thickness limitation, crystalline quality variation, and substrate clamping, and more importantly, it provides a more intrinsic and reliable way to study strain-controlled behaviors in functional oxide systems. It is found that both the saturation magnetization and coercivity of the transferred films can be changed over the bending status and show a high accord with the movement of the curvature bending radius of the polyimide substrate. This reveals that the mechanical strain plays a critical role in tuning the magnetic properties of CFO thin films parallel and perpendicular to the film plane direction.

Polycrystalline CVD diamond typically has inhomogeneous structure in cross section, with grain size monotonically increasing from bottom (nucleation) side to top (growth) side, this resulting in a significant difference in local thermal conductivity in the layers adjacent to the two surfaces. The polycrystalline diamond films with both sides of similar structure with coarse-grains are of interest for thermal management applications. Here, we produced a double-side coarse-grain polycrystalline diamond film by microwave plasma assisted chemical vapor deposition (MPCVD), by a repeated diamond growth on nucleation side of a primary free-standing film. The grain size, texture, morphology and phase purity of the samples were characterized with SEM, XRD and Raman spectroscopy, while the thermal conductivity (TC) perpendicularly to the film plane was measured by a laser flash technique in the temperature range of 250–400 K. The thermal conductivity of a single layer and bi-layered films are found to be almost identical, while the local TC values for latter on both sides are expected to become similar. A simple model discretizing the film in two regions, “poor” and “good” diamond layers, is considered to explain the observed TC temperature dependences.

We have investigated the effect of spin-orbit-induced (SOI) magnetic fields on magnetization switching in GaMnAs films. The sign of such SOI fields depends on the direction of the current flowing in the film, thus providing a handle for electrically manipulating magnetization in ferromagnetic GaMnAs films. Specifically, when an applied magnetic field is swept along the current direction, magnetization reversal occurs via rotations in opposite sense (i.e., clockwise (CW) or counterclockwise (CCW)) depending on the sign of the current, thus leading to opposite signs of the planar Hall resistance (PHR) measured on the film. The effect of SOI fields also manifests itself through hysteretic behavior of PHR for two opposite currents as a fixed magnetic field is rotated in the film plane. The width of the resulting hysteresis between two current directions then allows us to estimate the magnitude of the SOI field at current density of 1.0 × 105 A/cm2 as ∼1.2 Oe in our GaMnAs film. Such switching of magnetization between two magnetic easy axes induced by switching the sign of an applied current provides a means of electronically controlling the value of film resistance (in this case of PHR), a process that can be exploited in spintronic devices.