Papers by SWARNAMAYEE MISHRA
Bulletin of Materials Science
We have investigated the magnetic and magnetoelectric properties of solid solutions in the green ... more We have investigated the magnetic and magnetoelectric properties of solid solutions in the green phase region of the 211-cuprate system Sm 2-x Nd x BaCuO 5 (x = 0.2, 0.4 and 0.6). These compounds crystallize in the centrosymmetric orthorhombic (Pnma) structure. Upon substitution of Nd, the antiferromagnetic ordering temperature of Cu 2? ions (T N1 = 24 K) and Sm 3? /Nd 3? ions (T N2 = 5 K) remain unchanged. Dielectric anomalies appear at T N1 under applied magnetic field, whose magnitude increases with field, and at T N2 = 5 K under zero magnetic field for all three compounds. Applied magnetic fields induce electric polarization at T N1 that vary linearly with magnetic fields. While the polarization decreases below T N2 in x = 0 and 0.2, it is enhanced for the samples with x = 0.4 and 0.6. Interestingly, an additional anomaly is observed in dielectric and electric polarization data at 23 K for the composition x = 0.4 under the magnetic fields. Our study reveals that the substitution of Nd significantly modifies the electrical properties due to changes in the interactions between 4f-3d moments.
APL Materials, 2020
Combining ferroelectricity and magnetism in the same material remains a challenge because it invo... more Combining ferroelectricity and magnetism in the same material remains a challenge because it involves complex crystal chemistry and stringent symmetry requirements. In conventional ferroelectrics, the polarization arises from the second-order Jahn–Teller effect associated with cations of d0 or s2 lone pair electronic configuration. In contrast, the magnetism arises from cations with partially filled d or f electrons. Materials that incorporate these two kinds of cations in different crystallographic sites exhibit multiferroic properties but with weak coupling between magnetism and ferroelectricity. On the other hand, a strong cross-coupling occurs in some materials, where specific spin structures induce weak ferroelectricity below the magnetic ordering temperature. In this article, we discuss a new class of multiferroics where the polar distortion results from chemical ordering. These polar oxides are mainly pyroelectric in the entire temperature range and exhibit magnetoelectric co...
Physical Review Materials
We report the synthesis, structure, and magnetism-induced multiferroic properties of the polar ma... more We report the synthesis, structure, and magnetism-induced multiferroic properties of the polar magnets RFeWO 6 (R = Tm, Sm, Gd, and Er). All these compounds crystallize in the orthorhombic structure with the polar symmetry Pna2 1 , which results from the ordering of Fe 3+ and W 6+ ions at different crystallographic sites. DC magnetization and specific heat measurements confirm the antiferromagnetic order of Fe 3+ spins at T N1 = 14−18 K and magnetic ordering of R ions at low temperatures. The magnetic order of Fe 3+ ions in these compounds is accompanied by a dielectric anomaly and a change in electric polarization. Intriguingly, a second ferroelectric transition occurs at the magnetic ordering temperature (T N2 = 5.5 K) of Tm 3+ ions in TmFeWO 6. The magnetic field dependent behavior of electric polarization varies with R ion, indicating the coupling between 4 f −3d spins. The emergence of change in ferroelectric polarization at the magnetic ordering temperatures demonstrates the multiferroic nature of the polar magnets RFeWO 6 (R = Tm, Sm, Gd, and Er). Our study indicates that the aeschynite type family of compounds with polar symmetry can be an excellent platform to understand the role of 4 f −3d coupling on multiferroicity.
Physical Review B
We report a comprehensive investigation of the structural, magnetic, and electrical properties in... more We report a comprehensive investigation of the structural, magnetic, and electrical properties in a quasi-twodimensional planar antiferromagnet BaNi 2 (PO 4) 2 , which crystallizes in the rhombohedral structure (space group R3) consisting of honeycomb layers of Ni 2+ ions. Magnetic susceptibility and heat capacity data reveal a longrange antiferromagnetic ordering of Ni 2+ ions at T N = 24 K. Interestingly, an applied magnetic field induces a dielectric anomaly and an electric polarization at T N with the polarization proportional to the applied magnetic fields, demonstrating the linear magnetoelectric effect in BaNi 2 (PO 4) 2 with a coupling coefficient of 1.67 ps/m. It is interesting to note that the magnetic symmetry associated with the magnetoelectric effect is1 , which allows all tensor elements of the magnetoelectric susceptibility.
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Papers by SWARNAMAYEE MISHRA