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Here we report the evidence of an additional magnetic ordering and frequency dispersive magneto-dielectric (MD) permittivity besides multiferroic behavior in Te4+ (S = 0) doped FeVO4. Two antiferromagnetic transitions similar to FeVO4 at ∼21.86 K (T N 1 ) and 16.03 K (T N 2 ) were observed in all samples. An additional novel defect clusters based magnetic ordering at relatively higher temperature (T A M O ) ∼ 203 K is also observed from the magnetization. Evaluated magnetic moments show systematic decrease and the magnetic frustration factors show an increase with the increasing of Te4+ (S = 0) content. MD studies show stable ferroelectric ordering at spiral magnetic transition (T N 2 ) and the multiferroic order persists to the largest doping of Te (x = 0.10). The MD studies also reveal a magneto-capacitive (MC) behavior at T A M O (∼203 K) with a high dielectric constant and loss, and the possible reason for the magnetic ordering and MC behavior is ascribed to short range magnetic clustering arising out of defect based mechanisms. Mössbauer spectroscopic studies confirm local structural correlation with magnetic and ferroelectric ordering.

Here, we report detailed studies on magnetic phase transitions and magneto-electric (ME) coupling in $$\text {Fe}_{1-x}\text {Ce}_x\text {VO}_4$$ . X-ray diffraction (XRD) and Raman spectroscopic measurements confirm triclinic crystal structure (P-1) with small variation in lattice parameters and Ce incorporation into the $$\text {FeVO}_4$$ lattice up to 10% of Ce. The presence of local lattice distortions and electronic inductive effect in $$\text {FeVO}_4$$ between $$\text {Fe}^{3+}$$ and $$\text {V}^{5+}$$ ions were found in X-ray absorption near edge structure (XANES) studies due to the presence of $$\text {Fe}^{3+}$$ –O– $$\text {V}^{5+}$$ linkages. Two antiferromagnetic (AFM) transitions similar to $$\text {FeVO}_4$$ appear at 21.86 K and 16.03 K, and Ce doping has little effect on the magnetic transitions. $$^{57}\text {Fe}$$ Mossbauer spectroscopic results show the invariance of Fe valance. Low temperature high magnetic field Mossbauer data depicts the presence of spiral AFM order in all the samples. A sharp peak at 16.0 K in dielectric permittivity with minimal suppression due to applied magnetic field is observed indicating the presence of ferroelectricity and magneto-dielectric coupling. Magnetic and ME transitions are almost robust against Ce doping.

The present work reports the structural, electrical and magnetic properties of W6+ and Mo6+ substituted four-layer Aurivillius compound, Bi5FeTi3O15 (BFTO). The oxidation states of the dopants and other elements of BFTO are studied from x-ray photo-electron and 57Fe Mossbauer spectroscopy. The substitution resulted in a net increase of magnetic cation (Fe3+) from 25% to about 37.5% in BFTO. However, the magnetization measurements indicate the lack of magnetic ordering even down to 2 K. Further, the high temperature (300-1070 K) dielectric study of these compounds reveal the ferroelectric transition temperature decreases with the increase of magnetic cations in BFTO because of hexavalent W6+ and Mo6+ substitution at Ti4+ site.

The present work reports the frequency dependent dielectric, ac-conductivity study across spin reorientation transition (TSRT) & Raman spectroscopy study across TSRT, Neel temperature (TN,Fe) of polycrystalline SmFeO3 (SFO). Anomalous variation is observed in phonon mode parameters for SFO across TSRT and TN,Fe indicating the presence of spin-phonon coupling similar to that of other RFeO3 compounds. Anomalous behavior is also observed in the temperature variation of dielectric constant and ac-conductivity across TSRT and frequency dispersion is observed at lower temperature side of TSRT.

We have investigated magnetic, structural and dielectric properties of Bi

The present work reports polarization response and the effects of

This paper presents study of ferro-elastic a-c domains evolution in BaTiO3 single crystal with electrical poling. The ferro-elastic domain populations corresponding to a-c domains are obtained from x-ray reciprocal space mapping experiments. Our results suggest for different poling fields different a-c domain configurations can be achieved which could help in achieving better piezo-electric properties. We’ve also found that a non-linear relationship governs c/a domain population ratio with poling fields.

A detailed account of magnetolattice coupling, magnetic frustration, and magnetoelectric effects in ${\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{VO}}_{4}$ ($x=0\ensuremath{-}1.0$) studied by temperature-dependent synchrotron x ray diffraction (SXRD), temperature- and magnetic-field-dependent dielectric permittivity $\ensuremath{\varepsilon}$, and magnetization measurements are presented in this paper where progressive Cr doping leads to structural transitions from triclinic (T)---monoclinic (M)---orthorhombic (O) symmetries. SXRD data shows an intricate relationship between magnetic, ferroelectric, and lattice degrees of freedom in these systems. ${\mathrm{FeVO}}_{4}$ reaches a magnetically ordered state with two successive antiferromagnetic orderings at ${\mathrm{T}}_{N1}$ (21.85 K) and ${\mathrm{T}}_{N2}$ (15.65 K), having collinear and noncollinear natures, respectively, as evidenced in DC magnetization measurements. Progressive ${\mathrm{Cr}}^{3+}$ incorporation at the ${\mathrm{Fe}}^{3+}$ site in ${\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{VO}}_{4}$ shifts these transitions to higher temperatures in T phase ($x=0.0$ and 0.10). At $x=0.175$ [in (T $+$ M) phase], these transitions become closer to each other. Beyond this concentration, a single broad antriferromagnetic transition is observed in M $(x=0.20\ensuremath{-}0.30$) and O ($x=0.90\ensuremath{-}1.0$) phases. A nonlinear behavior in isotherm M-H curves below ${\mathrm{T}}_{N2}$ indicates field-induced spin-reorientation transitions at higher magnetic field. In dielectric permittivity $\ensuremath{\varepsilon}$ a sharp peak at ${\mathrm{T}}_{N2}$ in T and near M regions with a minimal suppression because of applied magnetic field is found and no such peak is observed in far M phase. A discontinuity evidenced in electromagnetic susceptibility indicates magnetoelectric effect at the polar to nonpolar transition regions. The structural incongruence in progressive transformation from T to M to O symmetries plays a vital role in controlling the nature of magnetic interactions. Our results indicate a strong correlation between structural transitions, magnetolattice coupling, magnetic frustrations, and magnetoelectric effect in ${\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{VO}}_{4}$.

We have investigated magnetic, structural and dielectric properties of Bi5FeTi3O15 (BFTO) in the temperature range 5K-300 K. Using diffraction, Raman spectroscopy and x-ray absorption fine structure measurements, iso-structural modifications are observed at low temperatures (≈100 K). The analysis of dielectric constant data revealed signatures of dielectric relaxation, concomitant with these structural modifications in BFTO at the same temperatures. Further, employing complementary experimental methods, it is shown that the distribution of Fe/Ti ions in BFTO is random. With the help of techniques that probe magnetism at various length and time scales, it is shown that the phase-pure BFTO is non-magnetic down to the lowest temperatures.

Thin films of four–layered Aurivillius Bi5FeTi3O15 compound were prepared using spin coating method. Phase purity of the sample is confirmed via X–ray diffraction and Raman spectroscopy measurements. Ferroelectricity in the prepared film is established from polarization versus electric field (P–E) loop measurements. The remnant and saturation polarization obtained from low temperature P–E measurements reveal a peculiar temperature dependence viz., decreasing on lowering the temperature. Apart from this, a development of an internal field in the system is observed towards lower temperatures which is reflected as biasing in the loops. Further, temperature dependent leakage current measurements have been performed and the analysis into conduction mechanisms shed light into the possible defect related mechanisms responsible for the aforementioned peculiar low temperature ferroelectric behavior. Also, the possibility of multiferroicity in the prepared film is explored with external magnetic field dependent P–E measurements and the results show very weak coupling between polarization and magnetic field.

Physical review / B covering condensed matter and materials physics 100(13), 134104 (2019). doi:10.1103/PhysRevB.100.134104, The structural and dielectric characterization of 30% Sn-doped BaTiO3 (BaSn0.3Ti0.7O3) as a function of temperature is carried out combining, complementary probes to reveal structural modifications associated to the relaxor behavior. Dielectric data confirms the existence of relaxor-type behavior in BaSn0.3Ti0.7O3. The local and average structural changes as a function of temperature have been investigated in the region of broad changes of dielectric response. Local probes, such as x-ray absorption fine structure spectroscopy and Mössbauer spectroscopy reveal a special trend of the lattice related to the diffuse dielectric phase transition as observed from dielectric data. The analysis of Raman spectra as a function of temperature reveals a peculiar behavior in the temperature region corresponding to the dielectric transition. The analysis of x-ray diffraction patterns points out a pseudocubic structure throughout the temperature range while the volume exhibits a negative thermal expansion in the region of broad dielectric maximum. Our results suggest structural modifications occurring in the system throughout a wide temperature range, interestingly, associated with changes in macroscopic properties of relaxors such as dispersion in dielectric constants and raising of dipole moments, Published by Inst., Woodbury, NY