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Fe3O4, as a half-metallic ferrimagnetic material, is believed to be one of the most promising materials in spin transport for spintronics. However, fabricating stoichiometric Fe3O4 film is still challenging because the oxidation is hard to control for various preparing methods. In this paper, series of Fe3O4 thin films on Si (100) substrates are grown by sputtering from a Fe3O4 target without oxygen atmosphere at different growth temperature and then extra heat treatment in high vacuum. By combining X-ray diffractometer (XRD), Raman spectrum, X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism, VSM analysis, we see that the structure and magnetic moment of Fe3O4 film are not only related with growth temperature during sputtering, but also refer to the temperature of post-heat treatments. When the growth temperature is lower than 300 °C, the film does not show any XRD diffraction peaks. When the growth temperature increases from 300 to 500 °C, the film shows the (111) texture of Fe3O4 film clearly. However, the other XRD diffraction peaks are observed after post-heat treatment. The saturation magnetization increases with growth temperature and the largest saturation magnetization is 473 emu/cm3 for growth temperature of 450 °C and extra heat treatment, which is close to bulk Fe3O4. Our results suggest that a selectable method can be used to fabricate high magnetic moment of Fe3O4 thin film.

Magnetic dynamic damping is significantly important in determining the relaxation time of magnetic moments and the speed of magnetic memory devices. Here, magnetic dynamic behaviors of permalloy (Py) films capped with gadolinium (Gd) are studied, and the effects of the interface are investigated by the Cu insert layer. For Py/Gd bilayer films, both the saturation magnetization ( ${M}_{s}$ ) and the surface anisotropy constant ( ${K}_{{\bot }}$ ) are decreased with increasing Gd thickness, while the Gilbert damping ( $\alpha$ ) is enhanced. With the insert of Cu at Py/Gd interface, the above tendencies of ${M}_{s}$ , ${K}_{\bot }$ , and $\alpha $ are suppressed. We attribute these phenomena to the antiferromagnetic coupling between Gd and Py near the interface, which are caused by the magnetic proximity effect (MPE) instead of the spin relaxation in the rare earth Gd themselves.

We investigate the current induced depinning of magnetic domain walls (DWs) trapped at the kinks in a patterned Py nanowire with two-kink zigzag shape on Si/SiO2 substrate. By injecting pulse current with varying amplitude, two threshold current densities with a slight difference of around $6 \times 10^{10}$ A m−2 have been determined according to the different depinning process. The smaller threshold current density corresponds to the depinning of a single DW which is always the first DW facing to the electron flow. This fact indicates that the different pinning potential caused by the structural asymmetry is not the key to determine which DW is to depin. Micromagnetic simulations provide evidence that the specific current-driven behavior of the vortex DW might account for the single depinning process. The larger threshold corresponds to the simultaneous depinning of two DWs which has been commonly observed in a variety of shaped nanowires. This asynchronous depinning phenomenon provides the possibility of the selective DW depinning in the future logic devices.

Magnetic semiconductors with high critical temperature have long been the focus in materials science and are also known as one of the fundamental questions in two-dimensional (2D) materials. Based on density functional theory calculations, we predict a 2D spin-gapless ferromagnetic semiconductor of CrGa2Se4 monolayer, in which the type of spin-polarized current can be tuned by tailoring the Fermi energy. Moreover, the magnetic anisotropy energy calculations indicate that the CrGa2Se4 monolayer possesses spin anisotropy both in the basal plane and the vertical plane. This originates from the distortion-induced rearrangement of the 3d electrons in the CrSe6 octahedron and results in an inclined easy axis out of the film. The Curie temperature (Tc) of ferromagnetic phase transition for 2D CrGa2Se4 is more than 200 K. This 2D material shows promising transport properties for spintronics applications and is also important for fundamental research in 2D magnetism.

Recent advances in two-dimensional van der Waals (2D vdW) magnets provide new platforms to study their magnetism in reduced dimensions. However, most of the studies performed to date have been limited to low temperatures. Here, we report the proximity effect of a 2D vdW magnet Fe3GeTe2 (FGT) on nickel (Ni) films at room temperature. Ferromagnetic resonance measurements show that FGT can increase the perpendicular magnetic anisotropy (PMA) and magnetic damping of the adjacent Ni film. Such an interfacial effect is observed at room temperature, and becomes more pronounced as the temperature decreases. A similar effect is also achieved in another 2D heterostructure of Cr2Ge2Te6/Ni, implying its universality in a variety of 2D magnetic materials. Our work provides a new approach for utilizing 2D magnets in spintronics at room temperature.

The spin dynamics modulation has attracted extensive attention in the past decades. Rare-earth (RE) metals are essential participants in this context due to the large spin–orbit coupling. Here, with neodymium (Nd) capping, we achieve the enhancement on spin dynamic damping of Co40Fe40B20 (CFB) films by three times larger than that of CFB single layer. Based on the spin pumping theory, the interfacial spin mixing conductance [Formula: see text] is calculated as 7.3 × 1015 cm−2, which is one order larger than that of CFB/Pt. It leads to the large spin current transparency at CFB/Nd interface. By comparing of the resistivity of each layer, we found that the matched resistivity at two sides of the CFB/Nd interface plays an important role in the enhancement of [Formula: see text]. As a consequence, a high spin transparency of the CFB/Nd interface is obtained as 82%. In addition, damping enhancement of CFB is not changed promptly by inserting 1–2 nm Cu layer, but it is suppressed when the Cu layer is thicker than 3 nm, which is related to the thickness dependence of the Cu resistivity. Our study broadens the horizon for the application of rare-earth (RE) in spintronics.

Recent advances in two-dimensional van der Waals (2D vdW) magnets provide new platforms to study their magnetism in reduced dimensions. However, most of the studies performed to date have been limited to low temperatures. Here, we report the proximity effect of a 2D vdW magnet Fe

Tunable magnetodynamic properties of magnetic materials will allow significant design freedom in spintronic devices. One of the most efficient methods to tailor magnetic properties is by element doping. Here, we study the effect of rare-earth (RE) doping on Permalloy (Py) films to modify the magnetic damping and exchange stiffness by both the ferromagnetic resonance uniform precession mode and the first perpendicular standing spin-wave mode. Results show that both static and dynamic magnetic properties of Py films are adjusted by doping with Gd, Tb, and Nd. The saturation magnetization is decreased by 59.4% with Tb, Gd, and Nd at concentrations of 10 at.%. The magnetic damping coefficient (α) is enhanced mostly by Tb dopant, followed by Nd and Gd, indicating that spin-orbit coupling may be one of the main mechanisms in determining α of RE-doped films. A 44.2% reduction of the exchange stiffness was achieved by doping with 3.3 at.% Nd. The results demonstrate that RE doping may be a viable technique for the control of magnetodynamic properties for spintronics applications.

Magnetic semiconductors with high critical temperature have long been the focus in materials science and are also known as one of the fundamental questions in two-dimensional (2D) materials. Based on density functional theory calculations, we predict a 2D spin-gapless ferromagnetic semiconductor of CrGa

Spin mixing conductance (SMC) at the ferromagnetic/non-magnetic material (FM/NM) interface governs the transport efficiency of the spin current. A high level of SMC is crucial for efficient spin injection and spin manipulation. Here, we report a reliable way to enhance the SMC at the FM/NM interface by rare-earth doping in the NM layer. As evidenced by the decreased saturation magnetization in permalloy (Py)/Cu–Nd structures, an induced magnetism in Nd is proposed, which is likely to be antiferromagnetically coupled to Py at the interface. By changing the doping content of Nd, the Py/Cu–Nd interface can be well designed, which gives rise to an effective tuning of the SMC from 0.37 × 1015 to 16.26 × 1015 cm−2. Such a tuning effect of SMC is suppressed by inserting a Cu spacer, demonstrating the key role of the antiferromagnetically coupled interface to the improved SMC. Our results highlight the significance of rare-earth materials in spin transport, expanding the design capability of energy-efficient spintronic devices.

We obtained epitaxial single-crystal Fe3O4(001)/MgO(001) thin films by magnetron sputtering. The high quality of the grown Fe3O4 films was confirmed by reflection high-energy electron diffraction and x-ray photoelectron spectroscopy. Atomic magnetic properties of Fe3O4(001)/MgO(001) were investigated using vibrating sample magnetometry and x-ray magnetic circular dichroism. The values of saturation magnetization and magnetic moment are 407 [Formula: see text] 5 emu/cm3 (3.26 [Formula: see text] 0.04 [Formula: see text]) and 3.31 [Formula: see text] 0.15 [Formula: see text], respectively, in the Fe3O4 film as thin as 5 nm, which are close to the bulk values. The spin polarization was directly measured using spin-resolved photoemission spectroscopy. The measured spin polarization has a maximum value of −42% [Formula: see text] 3%, which is comparable to the theoretical value for the ([Formula: see text] × [Formula: see text])R45° reconstructed Fe3O4(001) surface. Furthermore, the film thickness-dependent measurements indicate that the anti-phase boundaries significantly decrease the spin polarization rather than the lattice mismatch. Our results demonstrate that epitaxial Fe3O4(001)/MgO thin films grown by magnetron sputtering have desired magnetic properties, facilitating the potential application of Fe3O4-based spintronic devices.

Research in the spintronics community has been intensively stimulated by the proposal of the spin field-effect transistor (SFET), which has the potential for combining the data storage and process in a single device. Here we report the spin dependent transport on a Fe3O4/GaAs based lateral structured device. Parallel and antiparallel states of two Fe3O4 electrodes are achieved. A clear MR loop shows the perfect butterfly shape at room temperature, of which the intensity decreases with the reducing current, showing the strong bias dependence. Understanding the spin-dependent transport properties in this architecture has strong implication in further development of the spintronic devices for room-temperature SFETs.

Amorphous CoFeB films grown on GaAs(001) substrates demonstrating significant in-plane uniaxial magnetic anisotropy were investigated by vector network analyzer ferromagnetic resonance. Distinct in-plane anisotropy of magnetic damping, with a largest maximum-minimum damping ratio of about 109%, was observed via analyzing the frequency dependence of linewidth in a linear manner. As the CoFeB film thickness increases from 3.5 nm to 30 nm, the amorphous structure for all the CoFeB films is maintained while the magnetic damping anisotropy decreases significantly. In order to reveal the inherent mechanism responsible for the anisotropic magnetic damping, studies on time-resolved magneto-optical Kerr effect and high resolution transmission electron microscopy were performed. Those results indicate that the in-plane angular dependent anisotropic damping mainly originates from two-magnon scattering, while the Gilbert damping keeps almost unchanged.

Fe3O4 nanomaterials have attracted lastest interests due to their excellent properties and potential applications. In this paper, the thermal excitation is investigated by Mossbauer spectra and first principle calculations. Fe3O4 nanoparticles with uniform size, regular shape and good dispersibility are prepared by the solvothermal methods, and Fe3O4@SiO2 composite magnetic particles with layers of mesostructured SiO2 structure are assembled by improved Stober method. The particle size is 500 nm and the shell thickness of SiO2 layer is 80 nm. Fe3O4@SiO2 composite magnetic particles are then annealed at different temperature of 200 °C, 400 °C and 600 °C. The experimental measurements exhibit that the grain size grows up, and the magnetization is enhanced significantly, with increasing heat treatment temperature. However, Mossbauer spectra show that the relative absorption intensity in B-site fast decreases as increasing heat treatment temperature, from 64% at room temperature to 27% at 600 °C, indicating that large amount of Fe vacancies may form in B-site, and correspondingly, the net magnetic moment due to the difference of amount of Fe in B and A sites would be reduced, which strongly disagrees with the results of magnetization measured by vibrating sample magnetometer. In order to find the mechanism behind magnetization, the first-principle calculations are performed and reveal that the oxygen ions in the SiO2 shell may go into Fe3O4 core, which causes number of Fe2+ ions to decreases and transfer to Fe3+ ions, leading to the increase of magnetic moment. So we classify the difference between the amount of Fe3+ and Fe2+ ions in B-site as γ-Fe2O3. Based on this, Mossbauer spectra analysis presents quantitatively the concentration of various phase and their hyperfine interactions. This work provides a method to analyze the magnetic moment of Fe3O4.

Chromium tellurides have triggered tremendous investigations in physics and materials science, where their unique properties offer excellent opportunities for spintronic applications. Here, we report anisotropic magnetoresistance (AMR) of ferromagnetic CrTe single crystal flake grown by chemical vapor deposition. An individual hexagonal flake exhibits an easy magnetization axis along its normal direction, and cooling from room temperature to low temperature, its electrical resistance measured with the magnetization parallel to current geometry is larger than that for the perpendicular to the current geometry, indicating the presence of an AMR behavior. The AMR ratio has been found to increase with decreasing temperature and is 5.2% at 5 K, comparable with general magnetic transition metal and alloy. This suggests CrTe single crystal flake to be a promising magnetic material for spintronics applications.

Using the vibrating sample magnetometer and ex situ vector network analyzer ferromagnetic resonance, the static and dynamic magnetic properties of Tb (4 nm)/Cr ( t Cr )/Ni 80 Fe 20 (12 nm) trilayers with different thickness of Cr layer (from 0.2 to 4.0 nm) were investigated comparing with those of Ni 80 Fe 20 film. From the results of in-plane static magnetic hysteresis loops, we analyzed the soft magnetic properties and in-plane anisotropy, along with obtaining the saturation magnetization ( M s ) which shows no obvious reducing and a modulation akin to RKKY coupling. By fitting the relationship of resonance field and linewidth versus resonance frequency, the effective magnetization 4π M eff , gyromagnetic ratio γ , and effective damping coefficient ( α eff ) were extracted. It is worthwhile to mention that the inserting of ultrathin Cr layer (0.2 nm) enhanced the above parameters obviously, which then backed down towards their values in Ni 80 Fe 20 film with increasing the thickness of Cr layer as a result of the weakening magnetic proximity effect and the decreasing spin-pumping effect in trilayers. Finally, they became flattening with the Cr layer thicker than 1 nm where oscillations are also observed in the value of γ and α eff. Interestingly, the oscillations in α eff and γ are consistent with each other, which implies the damping mechanism mainly related to the spin-orbit coupling originating from the indirect interaction between Tb and Ni 80 Fe 20 . In addition, the inhomogeneous broadening (Δ H 0 ) were determined to be very small which further ascertain the accurate of the α eff .

The strong (111)-textured ZnxFe3−xO4 thin films were grown on SiO2-terminated silicon substrates using pulsed laser deposition. X-ray diffraction and high resolution transmission electron microscopy clearly show the column growth structure along the film thickness direction in [111] crystalline orientation for every grain column. With the introduction of texture induced magnetic anisotropy in the free energy density model, we quantitatively determined the doping effect on the various anisotropies in (111)-textured ZnxFe3−xO4 films. The mechanisms of ferromagnetic resonance linewidth of ZnxFe3−xO4 thin films are investigated by the theoretical fitting, in which considering the contributions from intrinsic spin-orbit coupling, extrinsic compositions from two-magnon scattering and inhomogeneous broadening. It is found that the Gilbert damping coefficient α increases with increasing Zn substitution x from 0 to 0.3, indicating that the spin-orbit coupling of the ZnxFe3−xO4 thin films increases with the introduction of Zn impurities.

Ferromagnet/two-dimensional transition-metal dichalcogenide (FM/2D TMD) interfaces provide attractive opportunities to push magnetic information storage to the atomically thin limit. Existing work has focused on FMs contacted with mechanically exfoliated or chemically vapor-deposition-grown TMDs, where clean interfaces cannot be guaranteed. Here, we report a reliable way to achieve contamination-free interfaces between ferromagnetic CoFeB and molecular-beam epitaxial MoSe2. We show a spin reorientation arising from the interface, leading to a perpendicular magnetic anisotropy (PMA), and reveal the CoFeB/2D MoSe2 interface allowing for the PMA development in a broader CoFeB thickness-range than common systems such as CoFeB/MgO. Using X-ray magnetic circular dichroism analysis, we attribute generation of this PMA to interfacial d-d hybridization and deduce a general rule to enhance its magnitude. We also demonstrate favorable magnetic softness and considerable magnetic moment preserved at the interface and theoretically predict the interfacial band matching for spin filtering. Our work highlights the CoFeB/2D MoSe2 interface as a promising platform for examination of TMD-based spintronic applications and might stimulate further development with other combinations of FM/2D TMD interfaces.

Interfacial effect of amorphous cobalt-iron-boron (Co60Fe20B20) films deposited on GaAs(001) by DC magnetron-sputtering has been precisely studied. In-plane uniaxial magnetic anisotropy (UMA) as a significant magnetic property has been found in Co60Fe20B20/GaAs heterostructure and the UMA field (Hu) of (∼75 Oe) is achieved. Magnetic Schottky barrier contact has been achieved by current-voltage (I–V) characteristic through the interface with a barrier height of 0.72 eV, which is an appropriate for tunneling injection of spin current from ferromagnet to semiconductors in spin-injection devices.

By analyzing the in-plane angular dependence of ferromagnetic resonance linewidth, we show that the Gilbert damping constant in ultrathin Fe3O4 epitaxial films on GaAs substrate can be enhanced by thickness reduction and oxygen vacancies in the interface. At the same time, the uniaxial magnetic anisotropy due to the interface effect becomes significant. Using the element-specific technique of X-ray magnetic circular dichroism, we find that the orbital-to-spin moment ratio increases with decreasing film thickness, in full agreement with the increase in the Gilbert damping obtained for these ultrathin single-crystal films. Combined with the first-principle calculations, the results suggest that the bonding with Fe and Ga or As ions and the ionic distortion near the interface, as well as the FeO defects and oxygen vacancies, may increase the spin–orbit coupling in ultrathin Fe3O4 epitaxial films and in turn provide an enhanced damping.

Magnonic devices are promising alternatives to conventional charge-current-driven spintronic devices. As the basic unit of spintronic devices, the spin valve is of limited use in magnonics because its dynamics is rarely studied. Here, we investigate the interlayer transmission of magnons in dynamic spin valve structures using the time-resolved magneto-optical Kerr effect. Interaction between magnons and the interfacial dissipation are studied by comparing three samples with different spin valve structures. Magnons with different intrinsic frequencies have strong interactions. In contrast, magnons with similar intrinsic frequencies have relatively weak interactions. Interfacial dissipations of magnons are increased by rare earth insertion, which can reduce the interactions between magnons indirectly. This work extends the application of spin valve structures to magnonic devices beyond their conventional use.

Polycrystalline Fe3O4 films with the thickness of 27 nm were grown at different temperature (Ts) on Si (100) substrate by Laser-Molecular Beam Epitaxy to study the influence of density of antiphase boundaries (APBs) and the spin polarization of Fe3O4. Films prepared with Ts in the range of 500 °C - 650 °C were proved to be of good crystallization, preferred orientation, and desirable values of saturation magnetization (a little smaller one for film prepared at Ts = 500 °C). The lowest density of APBs was verified by the measured bulk like electron-phonon (s-p) coupling constant for film prepared at Ts = 550 °C, along with the highest value of spin polarization and the best crystalline quality as the most obvious inflection in the curves of lnρ vs. 1000/T around Verwey transition. This optimum value of Ts can be interpreted by the APBs thermally activated migration process with an activation energy. Films prepared with Ts = 500 °C, 600 °C, and 650 °C still have a reasonable value of the s-p coupling constant compared to recently reported results, while larger magnetoresistance accompanied by the superparamagnetic behavior was observed for films prepared at lower Ts (Ts = 400 °C and 450 °C).

As an important parameter for characterizing the magnetization dynamics, Gilbert damping constant α in a thin film or a multilayer is generally extracted from the linear fitting of the frequency-dependence of the ferromagnetic resonance linewidth, sometimes accompanied with a tiny deviation of the linewidth to a smaller value at the low-frequency or high-frequency region due to the two-magnon scattering with an in-plane-field configuration, in which an in-plane magnetic field H perpendicular to a microwave field h was applied in film plane during measurement. In contrast, here we report, in ultrathin Gd/Cr/Fe multilayers, an anomalously large linewidth in the film plane at the low-frequency region. For the first time, we have successfully extracted the Gilbert damping constant from perfect theoretical fitting to the experimental data, by considering the effective direction of the magnetization around in precession staying out of the film plane when the in-pane H at which the precession starts is below the saturation field. This magnetization deviation from the film plane is found to have an obvious contribution to the enhanced linewidth caused by two magnon scattering, while slightly reduce the intrinsic linewidth. Under the same resonance frequency, the deviation angle reaches the maximum values at tCr = 1.0 nm while decreases when tCr increases to 1.5 nm, which coincides with the trend of the surface perpendicular anisotropy constant K⊥. A reduced intrinsic damping constant α is obtained as the introduction of Gd layer and Cr layer as a result of the competition between the spin pumping effect and the interfacial effects at the Fe/Gd and Fe/Cr interfaces. While the decreasing α for film with Cr layer thickness increasing to 1.5 nm might means the contribution of the electron density of states at the Fermi energy n(EF). This study offers an effective way to accurately obtain the intrinsic damping constant of spintronic materials/devices, which is essential for broad applications in spintronics.

The Tb(4 nm)/Cr( ${t}$ nm)/Fe(5 nm) trilayers with different thicknesses of Cr layer have been investigated by X-ray diffraction, vibrating sample magnetometer, and ferromagnetic resonance. When Cr is thinner than 1.8 nm, the ferromagnetic coupling of Tb and Fe leads to higher saturation magnetization ( $M_{s}$ ) than that of Fe(5 nm) film. On the other hand, the Gilbert damping constant $\alpha $ in all the trilayers have been found to exceed the magnitude of the Fe. In particular, when Cr layer is 1 nm thick, $\alpha $ increases by 38% and $M_{s}$ is increased by 6%; when Cr layer is 4 nm thick, $\alpha $ is increased by 46%, while $M_{s}$ is only decreased by 5%. Accordingly, we have demonstrated a way for enhancing damping and magnetic moment simultaneously in the Tb(4 nm)/Cr( ${t}$ nm)/Fe(5 nm) trilayers.

A 3.5 nm amorphous CoFeB film was sputtered on GaAs (001) wafer substrate without applying magnetic field during deposition, and a significant in-plane uniaxial magnetic anisotropy (UMA) field (Hu) of about 300 Oe could be achieved. To precisely determine the intrinsic Gilbert damping constant (α) of this film, both ferromagnetic resonance (FMR) and time-resolved magneto-optical Kerr effect (TRMOKE) techniques were utilized. With good fitting of the dynamic spectra of FMR and TRMOKE, α is calculated to be 0.010 and 0.013, respectively. Obviously, the latter is 30% larger than the former, which is due to the transient heating effect during the TRMOKE measurement. In comparison with ordinary amorphous CoFeB films with negligible magnetic anisotropies, α is enhanced significantly in the CoFeB/GaAs(001) film, which may be mainly resulted from the enhanced spin-orbit coupling induced by the CoFeB/GaAs interface. However, the significant in-plane UMA plays minor role in the enhancement of α.

Fe3O4 particles with uniform size, regular shape and good dispersibility are prepared by solvothermal methods. The size of Fe3O4 particles and their magnetic properties can be adjusted during synthesis. Fe3O4@SiO2 composite magnetic particles with layers of mesoporous SiO2 structure are assembled by improved Stöber method. The different shell thickness of SiO2 layer can be adjusted from 35∼150 nm using multi-coating by changing the content of TEOS to form Fe3O4@nSiO2@mSiO2. The Mössbauer spectra show that Fe3O4 particles are almost stoichiometric. However, it is found that the coverage of SiO2 have a significant effect on the occupation of Fe ions in Fe3O4 particles. Peroxidation appears in Fe3O4@SiO2 composite magnetic particles, which might be caused by oxygen in SiO2 layer during wrapping process.

By analyzing the in-plane angular dependence of ferromagnetic resonance linewidth, we show that the Gilbert damping constant in ultrathin Fe

The samarium doping zinc oxide (Zn 1– x Sm x O) with ( x =0.0, 0.04, 0.05 and 0.17) polycrystalline thin films have been deposited on n-Si(1 0 0) substrate using thermal evaporation technique. Ceramic targets for deposition were prepared by the standard solid-state reaction method and sintered in nitrogen atmospheres. X-ray diffraction and scanning electron microscopy analyses show that the bulk and films features reveal wurtzite crystal structure with a preferential (1 0 1) crystallographic orientation and grows as hexagonal shape grains. According to the results of the Hall effect measurements, all the films show p-type conductivity, possibly a result of nitrogen incorporation into the Sm-doped ZnO samples. Magnetic measurements show that ferromagnetic behavior depends on the Sm 3+ concentration. For a film with lower Sm 2 O 3 contents ( x =0.04), a phenomenon of paramagnetism has been observed. While, with further increase of Sm 3+ contents ( x =0.05) the ferromagnetic behavior has been observed at room temperature. However, at higher doping content of Sm 3+ , the ferromagnetic behavior was suppressed. The decrease of ferromagnetism with increasing doping concentration demonstrates that ferromagnetism observed at room temperature is an intrinsic property of Zn 1– x Sm x O films.

The mechanism of the magnetic properties on the Zn2+ substituted Fe3O4 film have been investigated based on first principle calculations. It is found that the surface effect plays an important role in the occupation of Zn ion, and in turn changes the magnetic moment. It may also destroy the half metallic behavior of Fe3O4 film even if the Zn2+ concentration only is one Zn2+ per unit cell (4%), which is different from that in bulk material.

Focusing on the Ni80Fe20 (Py)/Nd-Cu bilayers, the magnetization dynamic damping from spin pumping effect is investigated systematically by doping itinerant Cu in rear earth metal Nd. Various Ta/Py/Nd1-xCux/Ta/Si films with x = 0%, 16%, 38%, 46% and 58% are prepared by magnetron sputtering. For every content of Cu, the thickness of Nd-Cu layer is changed from 1 nm to 32 nm. The damping coefficient increases with increasing the thickness of Nd-Cu layer, which shows the trend of the spin pumping behavior. Also, with increasing Cu concentration in the Nd-Cu layer, the damping coefficient decreases, implying that the spin-orbit coupling in Nd-Cu layer is indeed cut down by high itinerant of Cu dopants. It is interesting that the spin diffusion length (λSD) in the Nd-Cu layer for different Cu dopants is not found to increase monotonously.

Single-crystal Fe dot arrays with the lateral size varying from 400 nm to 50 nm are fabricated by focused ion beam (FIB) direct writing from a single-crystalline 10 monolayer (ML) Fe (100) continuous thin film grown on GaAs substrate. The Kerr hysteresis loops of both dot arrays and continuous thin film are measured by focused magnetooptical Kerr effect (MOKE) measurements along four major crystal directions: [0-11] [010] [011] and [001]. It is found that the in-plane uniaxial anisotropy has been greatly reduced down to zero in the dot arrays when the size is less than 150 nm. The micromagnetic simulations confirm the reduction of this intrinsic in-plane uniaxial anisotropy in the patterned dots by separating the effect of the shape anisotropy. The experimental and simulation results further indicate an additional magnetic uniaxial anisotropy along the [010] direction.

A series of Fe3O4 particle chains with an average particle diameter of 150 nm and different lengths were synthesized by using the self-assembly method at reduced temperature in different synthesizing magnetic fields. The influence of synthesizing magnetic field on the properties of the magnetite particle chains was studied by structural analyses, magnetometry measurement, and ferromagnetic resonance. A uniaxial magnetic anisotropy in the saturation field (Hs), hysteresis loop, and ferromagnetic resonance were observed to increase with increasing synthesizing field. The saturation magnetization and g-factor were found to increase slightly with increasing synthesizing field. The demagnetizing fields and demagnetizing factors were determined from the experimental data of magnetometry measurement, ferromagnetic resonance, and also numerical calculation, which agreed reasonably well. It was found that the magnetization non-uniformity in the chains and the magnetostatic interaction among the chains have an impo...

Magnetic anisotropies of Fe/MgO/GaAs(100) hybrid structure with two different nonmagnetic capping materials, Au and MgO have been studied by ferromagnetic resonance (FMR). A uniaxial anisotropy, unexpected from the crystal structure was observed in the ultrathin films for both capping materials. Its global easy axis is along [0-11] direction while two (010) directions are equally magnetic hard regardless of the overlayer material. The in-plane uniaxial anisotropy (in-plane cubic anisotropy) of the Au capped samples is stronger (weaker) than that of the MgO capped ones within the range of t Fe = 7.1 to 28 ML. This suggests that the MgO overlayer suppresses the uniaxial anisotropy faster than the Au overlayer.

It is well-known that heavy Rare Earth (RE) metal of Tb, with stronger coupling of orbital and spin moments and anisotropic magnetism, can influence the magnetic properties of Fe based soft magnetism, especially tailor magnetization dynamic damping and in turn influence the magnetization switching time [1], [2], [3]. In our previous work, the dynamic damping of Fe-based films with dilute RE(Tb, Nd) dopants is indeed enhanced [4], [5], and even for the bilayers of Permalloy/ Nd(Tb), damping constant is increased strongly by spin pumping effect. However, the magnetic moments of Tb and TM are found to be antiferromagnetic coupling with each other, which reduces the net magnetic moment greatly. It is reported that the Tb film grown on the Fe layer, separated by ultrathin Cr layer can solve the problem based on the principle of RE-metal moments coupling antiferromagnetically with Cr, and Cr in turn coupling antiferromagnetically with Fe [1]. Hence, an effective ferromagnetic coupling is expected between the RE and the Fe magnetic moments to enhance the saturation magnetization, at the same time to remain a higher damping constant in the combination of RE/Cr/Fe multilayers.

The magnetic anisotropies are one of the dominating factors affecting the behavior of magnetic materials, which is profoundly evident in magnetic ultrathin films, and significant in the application of information storage and magnetic sensor field. Extensive studies of magnetic anisotropies in various films have been carried out. It is well known that the contribution of magnetocrystalline anisotropy is negligible in isotropic polycrystalline films while essential in single-crystal films. However, in textured film, a polycrystalline film composed of nanograins with the near same lattice orientation, the competing interactions between magnetocrystalline and other anisotropy is still an open issue. The quantitative investigations on the contribution of magnetocrystalline anisotropy in the textured film are rarely reported. In this paper, the expression of magnetocrystalline anisotropy energy in textured film (texture anisotropy energy) is given, and angle-resolved FMR studies on the textured Fe 3 O 4 film is also presented.