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In order to acquire a soft magnetic film with low conductivity and large magnetic anisotropy, the strain-modulated magnetic anisotropy is studied in epitaxial MgFe2O4 (MFO) films. The MFO films with thicknesses of 25, 48, 75, and 110 nm are grown on the MgAl2O4 (MAO) (100) substrate using a pulsed laser deposition technique. Due to the large lattice-mismatch (3.34%) between MFO and MAO substrates, the interface exhibits a large tetragonal compressive strain. The results of field-dependent magnetization suggest the soft magnetic nature of all the measured MFO films. The analysis of angular dependent ferromagnetic resonance reveals the large uniaxial magnetic anisotropy energy (Ku) of −1.62 × 106 erg/cm3 in the highly strained 25 nm film, and Ku decreases with the increasing thickness due to strain relaxation. The observed large magnetic anisotropy in these highly strained MFO thin films is larger than most of the soft ferrite thin films, which arise due to tetragonal distortion and inverse magnetostriction. The epitaxial MFO thin films with enhanced magnetic anisotropy could be one of the potential candidates for spin filters. [ABSTRACT FROM AUTHOR]

Singlet exciton fission is a spin-allowed process in organic semiconductors by which one absorbed photon generates two triplet excitons. Theory predicts that singlet fission is mediated by intermolecular charge-transfer states in solid-state materials with appropriate singlet-triplet energy spacing, but direct evidence for the involvement of such states in the process has not been provided yet. Here, we report on the observation of subpicosecond singlet fission in mixed films of pentacene and perfluoropentacene. By combining transient spectroscopy measurements to nonadiabatic quantum-dynamics simulations, we show that direct excitation in the charge-transfer absorption band of the mixed films leads to the formation of triplet excitons, unambiguously proving that they act as intermediate states in the fission process. [ABSTRACT FROM AUTHOR]

We obtain a large in-plane magnetic uniaxial anisotropy in the soft magnetic Fe60Co20B20 (FeCoB) thin films prepared by rotational sputtering. The anisotropy field (Ha) of 75 to 175 Oe was found in the films with wide ranged thickness from 2.5 to 100 nm, which was attributed to the magnetoelastic energy in association with anisotropic tensile stress. This stress-induced anisotropy has outstanding thermal stability that survives up to 350 °C in the annealing process. The similar large uniaxial anisotropy can be realized in other soft magnetic thin films, such as Fe, Co, Ni, FeCo, and NiFe, with the same synthesis technique. The anisotropic FeCoB film was used as a free layer in a synthetic spin valve. A linear resistance change against external field with a range wider than ±100 Oe together with a significantly reduced coercivity of ∼1.1 Oe (∼8.5 Oe in the case with isotropic free layer) was observed in the transfer curve. The results of this work not only confirm the feasibility of films with large stress-induced magnetic anisotropy as a functional layer in spin-valve devices but also demonstrate a simple synthesis route to induce the magnetic anisotropy, which provides an additional control parameter for the spintronic device design. [ABSTRACT FROM AUTHOR]

Pt Schottky contacts on (001)-orientated Nb-doped SrTiO3 (NSTO) in both ambient air and vacuum were investigated by the conductive atomic force microscope. The co-existed TiO2 and SrO termination layers were identified on the terrace-structured NSTO surface, where the former possessed a higher forward current than the latter. In ambient air, the barrier height of Pt/NSTO Schottky junction exhibited periodical variation with cyclic terrace plane and step sites, whereas it became homogeneous in ambient vacuum. We suggested that the oxygen absorption and releasing of surface dangling bonds were the origin for reversible changes in transport properties, which indicates a feasible approach for the surface modulation and band structure tailoring of NSTO based heterojunctions. [ABSTRACT FROM AUTHOR]

Critical analysis on the magnetic properties of synthetic ferrimagnet (SyF), Ta/MgO/CoFeB/Ru/ CoFeB/MgO/Ta, is demonstrated via both static and dynamic techniques. With the Ru thickness being 2.3 nm, the coupling between two CoFeB layers becomes orthogonal, which can be used for spin-transfer-torque nano-oscillator (STNO). The fitting of angular dependent ferromagnetic resonance (FMR) allows the precise determination of magnetic anisotropy of each CoFeB layer, the relative magnetizations and the exchange field near the frequency of STNO applications. In addition, the mechanism of resonance broadening at out-of-plane direction is identified to be magnetic inhomogeneity by fitting the angular dependent linewidth of FMR spectra, which provides indispensable information for the future design of STNO devices. [ABSTRACT FROM AUTHOR]

In this paper, Ag/Bi0.9La0.1FeO3 (BLFO)/La0.7Sr0.3MnO3 sandwich structure was grown epitaxially on SrTiO3 substrates using pulsed laser deposition. Short-circuit photocurrent (Ishort) and frequency dependence of the capacitance were investigated. It reveals that this heterostructure exhibits strong photocurrent responses, the orientation of Ishort depends strongly on the polarization orientations, and it varies monotonically from one orientation to the other as the polarization orientation switching gradually from upward (downward) to downward (upward), the Ishort value becomes zero when the film is in zero polarization states. The intensity of the Ishort can be strengthened by several times after thousands of bipolar electric pulses. Moreover, after polarization fatigue process of bipolar electric pulses or under light illumination, the capacitance of this sandwich structure is always bigger than the original state. However, the magnifying ratio of the capacitance after and before polarization fatigue process or under light illumination decrease with increasing the frequency in the C-f curves. These results suggest that polarization induced surface charge combined with migration of oxygen vacancies is the primary driving force for the varying of interfacial barriers and the oxygen vacancies density near the interface, which in turn leads to different orientations and values of Ishort as well as the differential interfacial capacitance. Our results indicate that the photovoltaic response in ferroelectric BLFO thin films could be further explored for solar light photovoltaic and other capacitor devices applications. [ABSTRACT FROM AUTHOR]

We include the effect of band non-parabolicity on photonic defect states within the Wannier theory, which improves the quadratic approximation adopted by Painter et al. [Phys. Rev. B 68, 035214 (2003)] for large-size defects, as well as extends the theory to a wider range of defect size. A 2D hexagonal photonic crystal is considered, and analyzed for the origin and degree of non-parabolicity in the 1st TE band around J-point, and for the effect of non-parabolicity on acceptor type cavity modes. The non-parabolicity is shown to derive primarily from the inherent anisotropy of band dispersion around the point. Overall, with the inclusion of non-parabolicity, (i) mode degeneracy is lowered, (ii) the 'binding energy' of a cavity mode is increased, and (iii) the cut-off of defect size for a given cavity mode is reduced, by as much as 35% in certain cases, in comparison with that calculated without the non-parabolicity. A simple 'overall effective mass' picture is provided for the understanding of non-parabolicity effects. [ABSTRACT FROM AUTHOR]

The oxygen vacancies in the SrTiO3 (STO) single crystal with two different cap layers, CoFe2O4 (CFO) and BiFeO3 (BFO), are investigated with the technique of electron paramagnetic resonance (EPR). EPR spectra show the resonance lines of the residual oxygen vacancy in air annealed STO, STO/CFO, and STO/BFO, showing the high sensitivity of EPR to the low concentration defects. The experimental results indicate that the oxide cap layers enhance the oxygen deficiency in bulk STO and the amount of oxygen vacancy is dependent on the electronegativity of metal ion in the cap layer. Accordingly, STO/BFO has a larger amount of oxygen vacancy than that of STO/CFO. [ABSTRACT FROM AUTHOR]

We present an approach for electrically manipulating nuclear spins in n-GaAs using an on-chip microcoil. Optically injected spin-polarized electrons are used to generate a dynamic nuclear polarization via electron-nucleus hyperfine interaction with a characteristic time constant of ∼10 min. The saturated Overhauser field amplitude is on the order of several 10 mT and proportional to the spin polarization degree of the injected electrons. Applying an rf field resonant for the 75As nuclei, complete depolarization of 75As nuclear spins is observed. [ABSTRACT FROM AUTHOR]

We have synthesized a series of LuMn1-xFexO3 (0⩽x⩽0.2) samples and study the effect of Fe-doping on their magnetic and dielectric properties. The magnetic characterization indicates that with increasing Fe-content up to 0.2, the antiferromagnetic (AFM) transition temperature increases from 90 to 105 K. A corresponding shift in the peak-positions of specific heat and dielectric anomaly is observed, indicating a strong correlation between the magnetic ordering and the electric polarization. Further analysis suggests that the rising of AFM transition temperature with increasing Fe-content should be from the structural origin, in which the strength of AFM interaction as well as the electrical polarization is dependent on the in-plane lattice parameters. [ABSTRACT FROM AUTHOR]

Multiferroic composites of NiFe2O4 (NFO) and BiFe0.5Cr0.5O3 (BFCO) are synthesized and their dielectric, magnetic, and magnetoelectr)ic (ME) properties are measured at room temperature. NFO-BFCO forms a two-phase composite. The composite has a larger magnetization and dielectric constant than those of both parent compounds, due to the effects of interfacial strain on BFCO. Furthermore, the ME response in NFO-BFCO is about one time larger than that of BFCO, revealing the success of magnetic control of the dielectric response via the mechanical coupling, which can be exploited in the future applications of multiferroic composites. [ABSTRACT FROM AUTHOR]

Magnetization reversal phenomena in submicron half-ring patterned wires with different corner structures have been investigated. The wires with corner structures of rectangular, semicircle, and triangular shapes were connected in series by two or five half-rings. The variation of domain structures with magnetic field is illustrated by electron transport measurements, simulation, and magnetic force microscopy (MFM) images. The switching behavior depends on the corner structures connecting the half-ring structures. These results are consistent with the domain pattern and magnetic phase shift observation provided by the MFM measurements. [ABSTRACT FROM AUTHOR]

Domain wall pinning force in the junctions (corners), with different shapes of square, semicircle, or triangle, of half-ring in-series wires is considered to study the current injection induced wall movements. This geometry has less thermal activation at the region of domain wall nucleation in contrast to notch structures. The wires with square corners have the largest domain pinning force to resist polarized current-induced magnetization reversal, judging from the largest slope in the current-field dependence (ΔI/ΔH=0.274). [ABSTRACT FROM AUTHOR]

We present a ferromagnetic resonance (FMR) spin pumping experiment at room temperature in periodic arrays of permalloy nanodots of different radii deposited onto a 3D topological insulator Bi2Se3 film. We measure the dc voltage signal generated by spin-to-charge conversion of the pumped spin current due to the spin-orbit coupling in the bulk of Bi2Se3. In the nanostructured samples, two resonance peaks are observed, associated with Kittel and inhomogeneous edge modes, respectively. This more complex modal composition in comparison to continuous systems may provide additional advantages for development of prospective spintronic devices. We support our experimental results by theoretical calculations, which are based on micromagnetic modeling of the magnetization dynamics under FMR excitation in a nanodot. A numerical approach to the calculation of the spin-pumping voltage is proposed, and the efficiency of spin-to-charge conversion is estimated for two nanostructured samples with different dot sizes. [ABSTRACT FROM AUTHOR]

Quasi-one-dimensional electron gases (q1DEGs) have been obtained by fabricating LaAlO3 nanowires, using the technique of electrostatic spinning plus post annealing, above TiO2-terminated SrTiO3 substrate. The q1DEG exhibits an electronic transport behavior of variable range hopping with the one dimension characteristic. Visible light illumination produces a strong effect on transport process, depressing the resistance of the q1DEG by a factor up to 8. As expected, gating effect is weak at relative high temperatures, ~3.2% at 150K and 1.5% at 300K under a back gate of 200 V. Aided by light illumination, however, the gating effect is 35-fold amplified, and the resistance increases under not only negative gates but also positive gates, different from the normal gating effect without illumination. Possible explanations for these phenomena are given. [ABSTRACT FROM AUTHOR]

Basing on conductive atomic force microscopy, we presented a direct conductance mapping for the interface of the La0.67Sr0.33MnO3/Nb:SrTiO3 hetero-junction. The most remarkable observation is the presence of an interfacial layer in Nb:SrTiO3 adjacent to the manganite film. Within this layer, the AFM tip/Nb:SrTiO3 contact shows a current-voltage dependence that strongly deviates from Shockley equation, unlike a Schottky diode. Spatial extension of this layer is explored and possible transport mechanism in or outside this interfacial layer is discussed. The present work gives a direct intuitional image on the interface of manganite junction. The principle proven here can be extended to other complex oxide interfaces. [ABSTRACT FROM AUTHOR]

The transmittance of tungsten oxides can be adjusted by oxygen vacancy (Vo) concentration due to its electrochromic property. Here, we report an in-situ observation of resistive switching phenomenon in the oxygen-deficient WO3-x planar devices. Besides directly identifying the formation/rupture of dark-colored conductive filaments in oxide layer, the stripe-like WO3-x device demonstrated self-regulated switching behavior during the endurance testing, resulting in highly consistent switching parameters after a stabilizing process. For very high V os mobility was demonstrated in the WO3-x film by the pulse experiment, we suggested that the electric-field-induced homogeneous migration of V os was the physical origin for such unique switching characteristics. [ABSTRACT FROM AUTHOR]

The short circuit photocurrent (Isc) was found to be strongly dependent on the oxygen vacancies (VOs) distribution in Ag/Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 heterostructures. In order to manipulate the VOs accumulated at either the Ag/Bi0.9La0.1FeO3 or the Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 interface by pulse voltages, switchable or nonswitchable photocurrent can be observed without or with changing the polarization direction. The sign of photocurrent could be independent of the direction of polarization when the variation of diffusion current and the modulation of the Schottky barrier at the Ag/Bi0.9La0.1FeO3 interface induced by oxygen vacancies are large enough to offset those induced by polarization. Our work provides deep insights into the nature of photovoltaic effects in ferroelectric films, and will facilitate the advanced design of switchable devices combining spintronic, electronic, and optical functionalities. [ABSTRACT FROM AUTHOR]

Complex impedance spectra of the low- and high-resistance states of Au/NiO/Pt and ITO/TiO2/ITO heterostructures were studied to probe the characteristics of conducting filaments (CFs). Different types of CFs were compared both qualitatively and quantitatively. It was demonstrated that important information of CFs, including the conducting behavior as well as the position and degree of rupture, can be obtained by analysis of the complex impedance data. We further employed this tool to explore resistive switching effect in HfO2 based heterostructures fabricated by different methods, and revealed the switching mechanisms and the effect of growth process on the properties of CFs. [ABSTRACT FROM AUTHOR]

Dynamic processes of resistance switching have been systemically investigated for the Ti/HfO2/Pt bipolar devices. Different transient characteristics were observed in the set and reset processes. The set process consisted of a waiting step and a following abrupt transition, whereas the reset process demonstrated a gradual resistance change. Nonlinear dependence of set time on pulse voltage was observed and explained by the thermally accelerated dielectric breakdown of local switching regions. The accumulation and dissipation effects observed for different pulse treatments strongly supported the proposed model, which suggests a possible approach to overcome the voltage-time dilemma. [ABSTRACT FROM AUTHOR]

We report on an experimental evidence of a significantly different dynamic nuclear polarization (DNP) for localized and itinerant electrons in n-GaAs. Optically injected spin-polarized electrons are used to generate dynamic nuclear polarization via electron-nucleus hyperfine interaction. Using time resolved Kerr rotation measurements for probing the transient Overhauser field, the DNP time constants for itinerant and localized electrons are extracted to be 10 min and less than 1 min, respectively. This is attributed to a rapid DNP occurring in the vicinity of the donors followed by a delayed nuclear spin polarization in between the donor sites. [ABSTRACT FROM AUTHOR]

The electro-osmotic flow through a wavy microchannel is studied under the Debye–Hückel approximation. An analytic solution by perturbation with appropriate averaging is carried out up to the second-order in terms of the small amplitude of corrugation. It is shown that the wavelength and phase difference of the corrugations can be utilized to control the flow relative to the case of flat walls. In particular, for thick electric double layers the electro-osmotic flow can be enhanced at long-wavelength corrugations because of the coherence between the electric potential and the wall shape function. Notably, these findings are not restricted to small amplitudes of corrugation. By applying the Ritz method to solve for the electro-osmotic flow, it is found that the enhancement becomes even greater (up to 30%) with increases in corrugation. Moreover, the nonlinear Poisson–Boltzmann equation is solved by finite difference to study the electro-osmotic flow in terms of the relative strength of the zeta potential. The issue of overlapped electric double layers when they are very thick is also discussed. The relative flow rate is shown to increase under the following conditions: (i) completely out-of-phase corrugations with long wavelength and large amplitude, (ii) small zeta potential, and (iii) slight overlapping of electric double layers. [ABSTRACT FROM AUTHOR]

GaN nanocolumns of exceptional crystalline quality have been grown by molecular beam epitaxy on both silicon (111) and sapphire (0001) substrates. Reflection high energy electron diffraction produces a unique diffraction pattern for in situ verification of columnar growth. Subsequent molecular beam epitaxial overgrowth of the nanocolumns has been used to improve the quality of thin film GaN layers when compared to GaN films grown directly on sapphire substrates. Transmission electron microscopy was used to confirm the absence of threading dislocations in the selected columns. Scanning electron microscopy of overgrown material demonstrated surface morphology similar to thin films grown in the intermediate (Ga-rich) growth regime, or a pattern of densely packed hexagonal structures, depending on growth conditions. Low temperature photoluminescence (PL) spectra demonstrated a greater than two orders of magnitude improvement in PL intensity of overgrown film versus direct film growth. [ABSTRACT FROM AUTHOR]

Bi0.9La0.1FeO3 (BLFO) thin films with the thickness of ∼500 nm were deposited on (001) oriented SrTiO3 substrate with 30 nm LaNiO3 as buffer layer. The switching kinetics process of ferroelectric BLFO thin films was investigated by using pulse voltages. The result shows that one dimension and two dimensions are the prior grown modes of BLFO domains in the polarization switching process. The dimensionality of the domain growth n increases linearly with applied voltage, and the grown model varies from 1 D (n = 1, implies needlelike growth) to 2 D (n = 2, planar growth) with electric pulses increasing. This is explained due to the increase in the density of nucleating domains at high fields where sideway growth is limited. The higher value of n can be an indication of non-homogeneous distribution of domain nuclei. Under all our experimental conditions that the switching time tsw is instrumentally limited and therefore the intrinsic switching time of ferroelectric BLFO films is smaller than several nanoseconds. This very short polarization switching time can be explained as a switching mechanism controlled by nucleation rate. Considering the domain walls de-pinning and thermal disturbance, the saturated polarization increases with the temperature increasing under the same input voltage which in turn affects the he switching transient current and switching time. [ABSTRACT FROM AUTHOR]

The resistive switching behaviors in the sandwiched Ti/HfO2/Pt devices with different doping condition were systematically investigated. We show that, comparing with the undoped and the Al layer doped HfO2 devices, significant improvement of switching characteristics is achieved in the Al local doped HfO2 device, including uniformity, reliability, and operation current. As a result, well controlled multiple switching states are obtained in the local doping device by modulating the set current compliance or the maximal reset voltage, respectively. Our results suggest that the switching characteristics of HfO2 device are very closely related to the inducement and controlling of conductive filaments' growth in the dielectric layer, which can be considered in the optimization of resistive random access memory device design. [ABSTRACT FROM AUTHOR]

Bipolar resistive switching (RS) behavior was observed in epitaxially deposited TiO2-δ/La2/3Sr1/3MnO3 stacks. An intermediate initial state of this device demonstrated that the original resistive state would switch to either the higher or the lower state, depending only on the electrical polarity of the initial measurement. As the analogue intermediate states were obtained by device fabrication, the direct observation of these switching states was possible, knowing the microscopic physical origin of the RS effect. Based on x-ray photoelectron spectroscopy analysis, an understanding of this interesting phenomenon was proposed, well supporting the oxygen vacancy formation and recombination mechanism. [ABSTRACT FROM AUTHOR]

Optically detected nuclear magnetic resonance (NMR) with micrometer resolution is demonstrated in n-GaAs using an on-chip microcoil. To trace the Overhauser field, the electron Larmor frequency is monitored via time-resolved magneto-optical Kerr rotation. Sweeping the frequency of the rf magnetic field induced by an on-chip microscale current loop, nuclear spin depolarization is achieved for each isotope species. The experimental data indicate an impact of a local quadrupole field, most likely caused by ionized donors, on the amplitude and linewidth of the NMR spectrum. By applying rf pulse sequences, the Rabi oscillation of 75As nuclear spins is obtained with an effective dephasing time of ∼200 μs. [ABSTRACT FROM AUTHOR]

A resistive switching device based on the stacked α-Fe2O3/Nb-SrTiO3 is proposed and fabricated that demonstrates excellent bipolar resistive switching behaviors including the uniformity, endurance, and retention performance. The Schottky-like current-voltage characteristics correlated with set process were observed in both high resistive states (HRSs) and low resistive states (LRSs) of the device. Importantly, the anticrosstalk characteristic, possessing higher reversed-biased LRS resistance than the forwarded-biased HRS resistance, indicates the potential applications of the stacked α-Fe2O3/Nb-SrTiO3 for multilevel storage in the cross-bar memory arrays. The carrier injection and trapping mechanism is suggested to explain the observed phenomena. [ABSTRACT FROM AUTHOR]

We have fabricated micrometer-sized single-turn coils on top of charged CdSe/ZnSe quantum dot heterostructures by lithographical techniques. Current injection creates magnetic fields in the some 10 mT range, strong enough to modulate the hyperfine interaction. The very low coil inductance allows for generation of fast field transients. We demonstrate local control of the resident electron spin as well as read-out of the nuclear spin state on the 10 ns time scale by electrical current pulses. [ABSTRACT FROM AUTHOR]

Electronic structures of strained Nd1-xCaxMnO3 (NCMO) thin films with x=0 to 0.8 are investigated via x-ray absorption spectroscopy (XAS). The obtained O 1s spectra within the photon energy 529–535 eV can be decomposed into eg↑1, eg↑2, t2g↓, and eg↓ bands. Based on the assigned energy levels of these band states, the energies of magnetic exchange, crystal field and Jahn–Teller (JT) splitting are determined. Particularly, the JT splitting is around 0.8 eV, which is observed with O 1s XAS for the first time in NCMO thin films. [ABSTRACT FROM AUTHOR]

X-ray absorption spectroscopy measurements have been performed to elucidate local electronic and atomic structures of orthorhombic 3d-transition metal-doped yttrium manganites (YMnO3) with chemical formulae YMn2/3Me1/3O3 (Me=Co, Ni, and Cu). The Mn L3- and K-edges x-ray absorption near-edge structure (XANES) demonstrate the direct substitution of Me2+ for Mn3+, so that the positive effective charge of Mn ions are increased. Me-doping is also found to induce substantial broadening of the Mn L3-edge feature, which suggests enhancement of the delocalization of Mn 3d eg subbands and conductivity. Local spin density approximation (LSDA)+U (Hubbard U parameter) calculations were used to understand their electronic structures. [ABSTRACT FROM AUTHOR]

We studied nanoscale elliptical ring shaped NiFe/Cu/NiFe trilayer pseudo-spin-valve structures. The magnetization reversal processes showed simultaneous-reversal single-step transition or double-step transition involving flux closure states. For various aspect ratios (short axis to long axis) and linewidths, transition between single-step and double-step magnetization reversals was measured to form a phase diagram. When the linewidth was reduced, edge roughness became important. Simulations of the magnetization reversal behavior agreed qualitatively with our results. [ABSTRACT FROM AUTHOR]

We demonstrate a method to electrically manipulate the spin polarization in a semiconductor on a micrometer length scale and a submicrosecond time scale. A variable magnetic field induced by a microscale current loop magnetizes the Mn2+ ions in a CdMnTe/CdMgTe diluted magnetic semiconductor quantum well, and via sp-d exchange interaction polarizes photogenerated electron-hole pairs. A maximum spin polarization degree of ±8.5% is obtained at 4.2 K without external magnetic field. The induced carrier spin polarization and the thermal heating of Mn2+ spins are resolved spatially and temporally by microphotoluminescence measurements. [ABSTRACT FROM AUTHOR]

A metal-oxide field-effect transistor (MOSFET) based on an electroluminescent conjugated polymer is fabricated on a glass substrate. It is found that the mobility horizontal to the substrate is two to three orders of magnitude larger than the mobility vertical to the substrate. The high horizontal mobility is attributed to the in-plane chain alignment in amorphous spin-coated films. We demonstrate an active pixel in which the light-emitting diode and the driving MOSFET share the same active polymer. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The annealing effects of perpendicular MgO/CoFeB/Ta structure are investigated with ferromagnetic resonance technique. The data of angular dependent resonance field, linewidth, and intensity are obtained for both as-grown and annealed samples. An increment of magnetic out-of-plane anisotropy field from 1800 to 3300 Oe with annealing is observed, which should be related to the improvement of crystalline at the interface. Ferromagnetic resonance linewidth significantly broadens after annealing, and this broadening is attributed to the enhancement of inhomogeneity of the internal field. [ABSTRACT FROM AUTHOR]

Multiferroic composites that comprise NiFe2O4(NFO) and Na0.5Bi0.5TiO3(NBT) are synthesized using the sol-gel method. The results of XRD and scanning electron microscopy indicate the single-phase formation of NFO and NBT and the presence of two phases in the composites. The dielectric constant and dielectric loss are determined as functions of frequency over a wide range of frequencies from 40 Hz to 1 MHz. Room-temperature magnetization measurements show that these composites are soft magnetic. Further, the multiferroic character is confirmed by their magnetoelectric (ME) response at room temperature. The optimal ME response is 0.14% in a 67NFO-33NBT composite. The present study demonstrates that NFO-NBT could be effective as a lead-free multiferroic composite and provides an alternative for environmental-friendly ME devices. [ABSTRACT FROM AUTHOR]