Showing papers on "Magnetocapacitance published in 2014"

Magnetocapacitance as a sensitive probe of magnetostructural changes in NiCr 2 O 4

Abstract: The spinel NiCr$_2$O$_4$ is characterized using dielectric and high magnetic field measurements. The trends in the magnetodielectric response fall into three clear temperature regimes corresponding to known magnetic and structural transitions. Above 65\,K, weak magnetic field dependence of the dielectric constant is observed with no hysteresis. When 30\,K\,$\leq\,T\,\leq$\,65\,K, a strong dependence of the dielectric constant on the magnetic field is observed and hysteresis develops resulting in so called butterfly loops. Below 30\,K, magnetodielectric hysteresis is enhanced. Magnetodielectric hysteresis mirrors magnetic hysteresis suggesting that spin-spin interactions are the mechanism for the magnetoelectric effect in NiCr$_2$O$_4$. At high fields however, the magnetization continues to increase while the dielectric constant saturates. Magnetodielectric measurements of NiCr$_2$O$_4$ suggest an additional, previously unobserved transition at 20\,K. Subtle changes in magnetism and structure suggest that this 20\,K anomaly corresponds to the completion of ferrimagnetic ordering and the spin driven structural distortion. We demonstrate that magnetocapacitance is a sensitive probe of magnetostructural distortion.

Structural, dielectric, magnetic, and optical properties of Ni0.75Zn0.25Fe2O4–BiFeO3 composites

Abstract: The magnetoelectric composites of spinel ferrite Ni0.75Zn0.25Fe2O4 (NZF) and BiFeO3 (BFO) with general formula xNi0.75Zn0.25Fe2O4 + (1 − x)BiFeO3 (x = 0, 0.10, 0.20, and 0.30) have been prepared via hybrid processing route. Subsequently, the effects of addition of NZF on structural, dielectric, magnetic, magnetoelectric, and optical properties of BFO have been investigated, and significant enhancements have been observed in physical observables such as grain size, dielectric constant, magnetization, and polarization in ferroelectric hysteresis loops. The variation of magnetization with temperature indicates the presence of spin glass behavior along with the ferromagnetic component. The magnetoelectric coupling is found with a value of magnetocapacitance to be 4.6 % for 30 mol% addition of NZF. The optical properties of the composites are also studied using UV–Vis diffuse reflectance spectroscopy, Photoluminescence spectroscopy, and FTIR spectroscopy.

Optically Tunable Magneto-Capacitance Phenomenon in Organic Semiconducting Materials Developed by Electrical Polarization of Intermolecular Charge-Transfer States

Abstract: DOI: 10.1002/adma.201305965 formed in organic donor:acceptor composites under photoexcitation through charge transfer in organic materials. [ 15,16 ] In particular, changing photoexcitation intensity can largely modify the density of intermolecular CT states and thus forms an effective tuning method on magneto-capacitance generated from intermolecular CT states. In this paper, we demonstrate the optically-tunable magneto-capacitance by using intermolecular CT states in organic donor:acceptor composites. Essentially, our magneto-capacitance from optically generated CT states can be also named as magneto-photocapacitance. Furthermore, we fi nd that changing the density of intermolecular CT states can lead to a tuning on both magnitude and line-shape of magnetocapacitance. In particular, the line-shape tuning suggests that the interactions between intermolecular CT states can affect the spin-exchange interaction within individual intermolecular CT states in the development of magneto-capacitance. We use the N,N ′-diphenylN,N ′-bis(3-methylphenyl)-1,1′biphenyl-4,4′-diamine (TPD) as donor and the 2,5-bis(5tert butyl-2-benzoxazolyl)-thiophene (BBOT) as acceptor for the generation of intermolecular CT states under photoexcitation. To prepare high-quality thin fi lms for device fabrication, the TPD and BBOT were dispersed into an inert poly(methyl methacrylate) (PMMA) matrix. The devices for capacitance measurements were made by sandwiching TPD:BBOT:PMMA composite fi lms between two electrodes (see Experimental section). The good quality of the fabricated devices can be shown by no detectable leaking current or injection current under driving voltages between −1 V and +1 V (Figure S1 in the supporting information). Figure 1 a depicts the magneto-capacitance from the ITO/TPD:BBOT:PMMA/Al device under photoexcitation. It can be seen that a photoexcitation can lead to a magnetocapacitance in the device when an alternating bias of 50 mV is applied without a DC bias during the capacitance measurements. Specifi cally, the capacitance increases quickly and then saturates around 80 mT with applied magnetic fi eld under photoexcitation, while no magneto-capacitance is observed under dark condition. It is also noticed that the pure TPD and BBOT do not exhibit such magneto-capacitance phenomenon under either dark or photoexcitation. Therefore, the magnetocapacitance phenomenon observed from the photo-excited TPD:BBOT:PMMA composite can be attributed to the intermolecular CT states formed between TPD and BBOT molecules. In general, magneto-capacitance can be developed through two different channels: magnetic fi eld-dependent electrical polarization and magnetic fi eld-dependent electrical current, namely polarization-based and transport-based magneto-capacitance. [ 1,17,18 ] Here, when a magnetic fi eld changes the singlet/ triplet ratio in intermolecular CT states, the polarization-based Magneto-capacitance, which can be produced by magneticallydependent electrical polarization in functional materials, [ 1,2 ]

Enhanced Multiferroic and Magnetocapacitive Properties of (1 − x)Ba0.7Ca0.3TiO3–xBiFeO3 Ceramics

Abstract: The structures, Curie temperature, dielectric relaxor behaviors, ferroelectricity, ferromagnetism, and magnetocapacitance of the (1−x)Ba0.70Ca0.30TiO3–xBiFeO3 [(1−x)BCT–xBF, x = 0–0.90] solid solutions have been systematically investigated. The ceramics have coexisted tetragonal (T) and orthorhombic (O) phases when x ≤ 0.06, coexisted pseudocubic (PC) and O phases when x = 0.065, coexisted cubic and O phases when 0.07 ≤ x ≤ 0.12, PC phase when 0.21 ≤ x ≤ 0.42, coexisted T and rhombohedral (R) phases when 0.52 ≤ x ≤ 0.70, and R phase when x ≥ 0.75. Significantly, composition-dependent microstructures and Curie temperature are observed, the average grain size increases from 1.9 μm for x = 0, reaches 12.0 μm for x = 0.67, and then decreases to 1.3 μm for x = 0.90. At room temperature, the ceramics with x = 0.42–0.70 show piezoelectric properties and multiferroic behaviors, characterized by the polarization-electric field, polarization current intensity–electric field, and magnetization–magnetic field curves, the composition with x = 0.67 has maximum polarization, remnant polarization, maximum magnetization, and remnant magnetization of 15.0 μC/cm2, 9.1 μC/cm2, 0.33 emu/g, and 0.14 emu/g, respectively. In addition, the magnetocapacitance is evidenced by the increased relative dielectric constant with increasing the applied magnetic field (H). With ΔH = 8 kOe, the composition with x = 0.67 shows the largest values of (er(H) − er(0))/er(0) = 2.96% at room temperature. The structure–property relationship is discussed intensively.

Enhanced magneto-electric property of GaFeO3 in Ga(1−x)ZnxFeO3 (x=0, 0.05, 0.10)

Abstract: Nanocrystalline samples of gallium orthoferrite (GaFeO3, GFO) and Zn doped GaFeO3 (Ga0.95Zn0.05FeO3, GZFO1 and Ga0.90Zn0.10FeO3, GZFO2) are prepared by sol–gel method. Crystallographic phase of each sample has been confirmed by analyzing the X-ray diffractogram using FULLPROF program and all the samples are grown in the distorted perovskite type structure. Magnetic measurements of all the samples are carried out in the temperature range of 300–4 K. Dielectric and ferroelectric measurements of the samples are also carried out at room temperature. Interestingly, the magnetization and electric polarization of the doped samples are enhanced compared to those of the pristine sample of GFO. The dielectric constant measured in presence and absence of a magnetic field confirmed that all the samples (GFO, GZFO1, and GZFO2) are type-II multiferroics and the magnetocapacitance is enhanced in the doped samples. The simultaneous enhancement of magnetization, polarization and magneto-capacitance co-efficient of the doped samples compared to that of GFO will be quite interesting for applications in electronic and memory devices.

Magneto-electric/dielectric and fluorescence effects in multiferroic xBaTiO3–(1 − x)ZnFe2O4 nanostructures

Abstract: Multiferroic composites of xBaTiO3–(1 − x)ZnFe2O4 (BTZF) [x = 0.25 (BTZF2575), 0.35 (BTZF3565), 0.45 (BTZF4555), 0.50 (BTZF5050) and 0.75 (BTZF7525)] nanostructure have been synthesized by a sol–gel method. Different types of nanostructural shapes and sizes have been obtained by the effect of ionic radii, surface energy and poly vinyl alcohol, which enhances the magneto-electric/dielectric interaction between BT/ZF phases. The crystalline phases of BTZF composite are confirmed by X-ray diffraction, and nanostructural dimensions and shape by transmission electron microscopy. The improvement in magnetization of BTZF is dependent upon the size and shape of the nanostructure, stoichiometric ratio and strength of occupation of cations at octahedral and tetrahedral sites. The chemical states of Fe in BTZF are analyzed by X-ray photoelectron spectroscopy. The ferroelectric property is explained by the nano size effect, 1D nanostructure shape, lattice distortion and epitaxial strain between two phases. The magnetoelectric coefficient is measured at room temperature under an applied dc magnetizing field and show different types of behavior in each sample. The magnetocapacitance is measured and explained on the basis of Maxwell–Wagner space charge and magnetoresistance, and relates to theoretical investigation, which proves that the enhancement not only depends on the size/shape of nanostructure but also the strain-induced phase transition where out-of-plane polarization appears in the composite. The photoemission of BTZF is observed by fluorescence spectroscopy.

Study of dielectric, magnetic and magnetoelectric behavior of (x)NZF-(1-x)PLSZT multiferroic composites

Abstract: The magnetoelectric composites (x)Ni 0.75 Zn 0.25 Fe 2 O 4 -(1-x)Pb 0.9 (La 0.96 Sr 0.04 ) 0.1 (Zr 0.65 Ti 0.35 ) 0.975 O 3 (for x variations 0, 0.20 and 1.0) where Ni 0.75 Zn 0.25 Fe 2 O 4 i.e. NZF is ferrite phase and Pb 0.9 (La 0.96 Sr 0.04 ) 0.1 (Zr 0.65 Ti 0.35 ) 0.975 O 3 i.e. PLSZT is ferroelectric phase, were synthesized via solid state reaction method. The presence of both the constituent phases was confirmed by X-ray diffraction studies. The microstructural analysis and grain size determination was carried out using field emission scanning electron microscope (FESEM). Variation of dielectric constant and dielectric loss with temperature at various frequencies (1 kHz and 10 kHz) was studied. The good ferroelectric behavior and ferromagnetic behavior of the composites were confirmed by Polarization versus Electric field (P-E) and Magnetization versus Magnetic field (M-H) measurements, respectively. The coupling between ferroelectric and ferromagnetic domains was confirmed through the observation of magnetic fieldinduced relative change in dielectric constant (Magnetocapacitance). The value of magnetocapacitance is found to be 2.6 % for the synthesized composite (with x=0.20). The fractional change of magnetic field induced dielectric constant can also be expressed as Δe~γM 2 and the value of γ is found to be ~8.16×10 -2 (emu/g) -2 for composite with x=0.20.

Magnetic, Magnetocapacitance And Dielectric Properties Of BiFeO3 Nanoceramics

Abstract: Single phase Bismuth ferrite (BiFeO3, BFO) nanoparticles (particle size ~ 50-100 nm) were synthesized by a novel chemical sol-gel technique. The detailed microstructural analysis has been performed through HRXRD, HRTEM and FESEM techniques. The nanoparticles are found to crystallize with distorted rhombohedral structure having R3c space group. The dielectric constant and tan δ loss are found to vary monotonically with temperature measured at different frequency ranging from 1 kHz to 1 MHz. The M (H) hysteresis behavior at 5 K reveals weak ferromagnetic nature of the BiFeO3 nanoparticles having coercivity (Hc) ~ 720 Oe and magnetization (Ms) ~ 1 emu/g at 5 T from SQUID measurements. The multiferroic character of BFO nanoparticles is confirmed through magnetoelectric response. The typical value of magnetodielectric response is observed to be 0.4% at 4300 Oe at room temperature at a frequency of 1 kHz. All the results suggest that the BFO nanoparticles are technologically very promising as far as magnetoelectric properties are concerned. Copyright © 2014 VBRI press.

Magnetocapacitance and loss factor of GaAs quantum Hall effect devices

Abstract: We present a simple and accurate coaxial bridge capable of measuring the magnetocapacitance and the associated loss factor of a quantum Hall effect device, with and without an external Hall current—a situation where commercial instruments are limited. We interpret the results in terms of the model of compressible and incompressible regions in the two-dimensional electron gas and we deduce a novel empirical relation between the loss factor and the voltage dependence of the magnetocapacitance. This highlights the reason for the linear voltage dependence of the loss factor whose elimination is the basis for all metrological applications of the quantum Hall resistance at alternating current.

Magnetocapacitance without magnetism.

Abstract: A substantial magnetodielectric effect is often an indication of coupled magnetic and elastic order, such as is found in the multi-ferroics. However, it has recently been shown that magnetism is not necessary to produce either a magnetoresistance or a magnetocapacitance when the material is inhomogeneous. Here, we will investigate the characteristic magnetic-field-dependent dielectric response of such an inhomogeneous system using exact calculations and numerical simulations of conductor–dielectric composites. In particular, we will show that even simple conductor–dielectric layers exhibit a magneto-capacitance, and thus random bulk inhomogeneities are not a requirement for this effect. Indeed, this work essentially provides a natural generalization of the Maxwell–Wagner effect to finite magnetic field. We will also discuss how this phenomenon has already been observed experimentally in some materials.

High-frequency magnetocapacitance effect in organic spin valve with a 3,4,9,10-perylene-teracarboxylic-dianhydride spacer

Abstract: The frequency-dependent impedance of a series of ferromagnet (FM)/organic semiconductor (OSC)/FM tri-layered organic spin valves (OSV) is investigated in the frequency range of 10 Hz–1 MHz. An equivalent resistor–capacitor (RC) parallel network model is employed to analyze the magnetoresistance (MR) and magnetocapacitance (MC) effects. Fitting with the model yields field-dependent parameters and the resistive parameters agree with the experimental results. The analysis of the impedance spectra indicates an effective magnetotransport mechanism dominated by the charge accumulation at the organic–FM interfaces.

Time-Reversal Symmetry Breaking and Consequent Physical Responses Induced by All-In-All-Out Type Magnetic Order on the Pyrochlore Lattice

Abstract: The physical properties of pyrochlore compounds with the all-in-all-out type arrangement of magnetic moments are discussed. The magnetic order can be regarded as a ferroic order of magnetic octupole moments, which does not give rise to macroscopic magnetization but breaks the time-reversal symmetry. As a result of the time-reversal symmetry breaking, the magnetostriction, magnetocapacitance, Voigt magnetooptic effect, and magnetic susceptibility are expected to have a term linear to the external magnetic field. Another striking consequence of the magnetic order is the presence of spontaneous magnetization and scalar spin chirality on the most stable {111} surfaces. This may pave the way for unique surface magnetotransport phenomena.

Theoretical study of magnetic spin correlations and the magnetocapacitance effect in BiMnO3

Abstract: The magnetic correlations between Mn ion spins and their effects on the magnetocapacitance in BiMnO3 are studied based on a microscopic model. Above the phase transition temperature of the magnetic subsystem, the magnetic correlations including the longitudinal and transverse parts are nonzero, and they lead to a nonzero specific heat of magnetic subsystem. We show that the magnetocapacitance effect is ascribed to the fluctuation of magnetic correlation. The linear relation between electric susceptibility and the magnetic correlation is obtained and the relevant experiments are explained.

Magnetodielectric behaviour in La0.53Ca0.47MnO3

Abstract: We explore magneto-dielectricity in La0.53Ca0.47MnO3 across its paramagnetic (PMI) to ferromagnetic (FMM) isostructural transition at TC ∼ 253 K, by magnetic (M), caloric (W), dielectric (e′), magnetoresistive (MR), and magnetocapacitance (MC) investigations. A skew-broadened first-order transition character is confirmed via heating/cooling hystereses in M(T) and W(T), with a superheating temperature T** next to TC and supercooling temperature T* exhibiting kinetics. Above TC, linearly related MC and MR reflect purely a magnetoresistance effect. Near TC, the high-frequency MC (5 Tesla (T)), far exceeds the magneto-losses, and is uncorrelated with dc MR (5 T) in the FM-ordered state. The intrinsic magneto-dielectricity manifest below TC and above ∼kHz is traced to an intra-granular Maxwell–Wagner-type effect at the interface region of PMI–FMM phase coexistence.

Fully valley- and spin-polarized magnetocapacitance in n-type monolayer MoS2

Abstract: We present a theoretical investigation on the quantum magnetocapacitance (MC) for n-type monolayer MoS2 under a perpendicular magnetic field. We find that the MC clearly reflects the valley- and spin-resolved Landau levels (LLs). Interestingly, the MC is fully valley- and spin-polarized, which results in perfect square-wave-shaped polarization. This fully valley- and spin-polarized MC, especially the peak corresponding to the lowest LL, may be of great significance in valleytronic and spintronic device applications because it provides a magnetic method to control the electron valley and spin degrees of freedom. The MC behavior as a function of the magnetic field is also discussed.

Colossal magnetocapacitance effect at room temperature

Abstract: First nano-hybridized clathrate/cavitant structure of hierarchical architecture was synthesized. The results of investigations of the properties of initial nanoporous silica matrices MCM-41, with encapsulated in its pores of β-cyclodextrin in cavitand and cavitat (with FeSO4) states and change at room temperature in a constant magnetic field intensity of 2.75 kOe, have been presented. Phenomenon of enormous magnetocapacitance and giant negative variable-current magnetoresistance has been discovered.

Magnetocapacitance Properties of Multilayered CoFe₂O₄/BaTiO₃/CoFe₂O₄ Thin Film by Pulsed Laser Deposition

Abstract: CoFe₂O₄(CFO)/BaTiO₃(BTO)/CoFe₂O₄(CFO) multilayered thin films were deposited on Pt/TiO₂/SiO₂/Si substrates by the pulsed laser deposition (PLD) system with KrF excimer laser (λ = 248 nm). BTO, CFO, BTO/CFO and CFO/BTO/CFO structured thin films were prepared and their crystal structures and microstructures, as well as their magnetic and magneto-electrical properties, were studied. The C-V characteristics of these multilayered thin films with different capacitor structures were obtained to confirm the change in their capacitances under a magnetic field. Finally, the capacitance of the CFO/BTO/CFO thin film as a function of bias voltage under an in-plane magnetic field of 1,000 Oe increased to 951.04 pF at 1 MHz, from 831.90 pF measured under no magnetic field, indicating 14.3% increase in magnetocapacitance.

Magnetocapacitance and impedance spectroscopy of Ba 0.7 Sr 0.3 TiO 3 /La 0.67 Sr 0.33 MnO 3 and Ba 0.8 Sr 0.2 TiO 3 /La 0.67 Sr 0.33 MnO 3 thin film heterostructures

Abstract: The paper discuses synthesis of Ba0.7Sr0.3TiO3/La0.67Sr0.33MnO3 and Ba0.8Sr0.2TiO3/La0.67Sr0.33MnO3 thin film heterostructures by sol–gel (citrate gel route) method. The XRD spectra are determined for confirmation of crystalline phases of Ba0.7Sr0.3TiO3, Ba0.8Sr0.2TiO3 and La0.67Sr0.33MnO3 thin films. The observed variation of Cp, tan δ, magnetocapacitance (Mc), real part of dielectric constant e′, imaginary part of dielectric constant e″as a function of frequency, magnetoresistance R(H) and magnetoimpedance Z(H) are presented in the paper. Further the observed impedance spectra as a function of frequency f is also presented in the paper. The observed variation of Mc is qualitatively correlated with the stress induced effect and magnetoresistasnce effect occurring simultaneously.

Effect of Sr substitution on structural, dielectric, magnetic and magnetoelectric properties of rapid liquid sintered BiFe0.8Ti0.2O3 ceramics

Abstract: Structural, dielectric, magnetic and magnetoelectric properties of polycrystalline Sr doped BiFe0.8Ti0.2O3 ceramics [Bi1−xSrx(Fe0.8Ti0.2)O3; x = 0.05, 0.10 and 0.15)] were studied. All the samples were prepared by rapid liquid phase sintering method. Rietveld refinement of X-ray diffraction patterns of all samples confirmed that the samples crystallize in a rhombohedral structure and showed change in Fe–O–Fe bond angle and Fe–O bond length which in turn enhanced magnetization from 0.33 to 0.73 emu/g with the increase in Sr concentration from x = 0.05 to 0.15. The dielectric constant and dielectric loss were observed to increase with the increase in temperature from 30 to 500 °C. An anomalous peak has been observed in dielectric constant versus temperature plot around 300 °C for all the samples, which is close to the magnetic transition temperature of BiFeO3. The composition-dependent magnetic properties with the expected Fe2+/Fe3+ ratio fluctuations were correlated by X-ray photoelectron spectroscopy. Magnetic and electric hysteresis loops showed a systematic increase in magnetization and polarization as a result of Sr doping in BiFe0.8Ti0.2O3 ceramics. The value of magnetocapacitance at 10 kHz was observed as 0.95, 1.23 and 1.73 for x = 0.05, 0.10, 0.15 respectively in Bi1−xSrxFe0.80Ti0.20O3 ceramics.

Dielectric modulus and magnetocapacitance behavior of Bi3.7Sm0.3Ti2.7Fe0.3O12 multiferroic

Abstract: This communication presents the dielectric and magnetodielectric studies of Bi 3.7 Sm 0.3 Ti 2.7 Fe 0.3 O 12 ceramic samples synthesized by a conventional solid state reaction method. X-ray diffraction (XRD) patterns reveal the formation of single phase orthorhombic structure. Dielectric measurements have shown anomalous behavior around 150 °C. Dielectric modulus analysis confirms the non-Debye type relaxation behavior at higher temperature. Room temperature weak ferromagnetism has been observed for Sm/Fe modified bismuth titanate ceramic with 2 M r value of 5.4×10 −3 emu/g. Magnetodielectric measurement shows the variation in dielectric constant value with applied magnetic field of 5 T, which confirms the magnetodielectric coupling in the system. The present results suggest a new material for room temperature multiferroic applications.

Magnetodielectric behaviour in

Abstract: We explore magneto-dielectricity in La0.53Ca0.47MnO3 across its paramagnetic (PMI) to ferromagnetic (FMM) isostructural transition at TC ∼ 253K, by magnetic (M), caloric (W), dielectric (e � ), magnetoresistive (MR), and magnetocapacitance (MC) investigations. A skew-broadened first-order transition character is confirmed via heating/cooling hystereses in M(T )and W( T ), with a superheating temperature T ∗∗ next to TC and supercooling temperature T ∗ exhibiting kinetics. Above TC, linearly related MC and MR reflect purely a magnetoresistance effect. Near TC, the high-frequency MC (5Tesla (T)), far exceeds the magneto-losses, and is uncorrelated with dc MR (5T) in the FM-ordered state. The intrinsic magneto-dielectricity manifest below TC and above ∼kHz is traced to an intra-granular Maxwell‐Wagner-type effect at the interface region of PMI‐FMM phase coexistence.

Structural, Dielectric And Magnetic Properties Of 0.3CoFe2O4-0.7BaTiO3-PVDF Composite Film

Abstract: Structural, Dielectric and magnetic properties 0.3 CoFe2O4–0.7 BaTiO3–PVDF (polyvinylidene fluride) composite film with different concentration of PVDF: 20, 30 and 40 wt% are reported here for the first time. The structural analysis was carried out using X-Ray diffraction technique, which indicates cubic spinel structure for ferrite phase CoFe2O4 (CFO) and tetragonal structure for ferroelectric phase BaTiO3 (BT). The average grain size was observed to be (~106 nm, 30 nm and 26 nm) for 20%, 30% and 40% addition of PVDF by using AFM analysis. The dielectric constant variation with temperature at three fixed frequencies (1 kHz, 50 kHz and 100 kHz) was studied and it was found that the dielectric constant and dielectric loss decrease with increasing amount of polyvinylidene fluride. The values of ac conductivity for 0.3CoFe2O4 – 0.7BaTiO3 –PVDF composite film were found to decrease with increasing concentration of PVDF. The ferroelectric hysteresis loops also indicate that the value of polarization decreases with the addition of PVDF and the value of remnant polarization for 20% PVDF was found to be 0.5286 μC/cm 2 . The magnetocapacitance of 0.3 CoFe2O4–0.7 BaTiO3–0.3 PVDF was found higher for this composition. Copyright © 2014 VBRI press.

Magnetoelectric Properties of NdxBi1-xFeO3 Thin Films

Abstract: Multiferroics based on BiFeO3 with spatially-modulated antiferromagnetic structure are investigated. The goal of this work is to define possibility of orientation phase transitions in magnetic and electric system by replacing Bi with 4f Nd ion depending on temperature in external magnetic field. On NdxBi1-xFeO3 films the measurements of permittivity, loss tangent at frequences 100 Hz < ω < 105 Hz and at temperatures 300 К < T < 1000 K without magnetic field and in magnetic field with H=0.8 Т were made. A drop in temperature dependence of permittivity in magnetic field was found. Magnetoelectric properties can be explained in model of changing of magnetic structure in magnetic field as a result of interaction of electric and magnetic subsystems.