Substantial magnetoelectric coupling in nanocrystalline-Fe2TeO6 at room temperature

Abstract

There is a confocal attention of the multifunctional material science and condensed matter physics research community to the room temperature (RT) magnetoelectric multiferroics through past several decades for its novel physical and chemical properties. Materials with substantial coupling at RT are still an unsaturated problem in the field of condensed matter physics. Apart from searching new magnetoelectrics, enhancement of the coupling as well as physical properties by manipulating the size dependency of these properties also very popular. Here, we report the presence of substantial magnetoelectric cooping in Nanocrystalline Fe 2 TeO 6 (FTO) at room temperature synthesized by sol-gel process. The nano aspect of FTO is confirmed from transmission electron microscopy, where the particles of sizes 10-40 nm are seen. Magnetic measurement on nano-FTO confirms the antiferromagnetic nature of particles having Nѐel temperature T N = 167 K, which is much lower than that of bulk (210 K). PE loop measurement at room temperature gives the remanent polarization (P r) value of 0.098 μC/cm 2 , confirming ferroelectricity in FTO. A nonmonotonous increase in the remanent polarization is noticed when an external magnetic field is applied on the sample. This is a clear indication of prevailing substantial magnetoelectric (ME) coupling in the sample at room temperature. Quantification of magnetoelectricity is done by directly measuring the ME voltage (V) in the presence of varying dc magnetic field (H) and the ME coefficients are obtained using a quadratic relation in H. Presence of ferroelectricity and magnetoelectricity above the Nѐel temperature is very unusual phenomenon in this material. The presence of short range magnetic ordering which prevails even upto RT, much higher that of long range magnetic ordering temperature is suspected to be responsible for this.

Short range magnetic correlation, metamagnetism and coincident dielectric anomaly in Na$_5$Co$_{15.5}$Te$_6$O$_{36}$

“…2(b)-(d)) have clearly indicated the respective charge states. The energy position of the Na 1s (1072.1 eV) clearly reveals the expected 1+ charge state 37 , while the peak positions of Te 3d doublets (576.8 eV, 587.2 eV) along with their energy separation (10.4 eV) suggest 6+ valance state of Te in NCTO 38 . The O 1s spectrum of NCTO has been fitted by considering two singlets (see the green and violet line of Fig.…”

Enhanced magnetic and room temperature intrinsic magnetodielectric effect in Mn modified Ba2Mg2Fe12O22 Y-type hexaferrite

“…Inside each block, spins of magnetic iron ions are collinearly aligned. At the boundary of magnetic blocks, superexchange interactions are responsible for not only setting of the long-range magnetic ordering but also stable helical spin ordering above RT [15][16][17][18][19][20][21][22][23][24][25]63]. From neutron diffraction and magnetization measurement, it is reported that Y-type hexaferrite undergoes ferrimagnetic to conical spin phase accompanied by proper screw phase as an intermediate spin phase manifested in figures 1(c)-(e) [26,27].…”

“…ME behavior in all these compounds can be explained by the presence of noncollinear magnetic spins originating due to inverse Dzyaloshinskii-Moriya (DM) interaction [5,13,14].To realize the magnetic control of ferroelectricity in the frustrated magnet systems, alternation or modification in spin state degeneracy is essential [15]. The robust ME coupling at RT is often noticed in antiferromagnets due to presence of strong superexchange interaction in between Fe 3+ ions [16]. Although, the direct quantification of ME coupling (measuring the influence of electrical polarization with magnetic field and vice versa) is not an easy task.…”