Rhombohedral distortion-driven ferroelectric order and exchange bias effect in geometrically frustrated ZnFe2O4

Abstract

The rhombohedral distortion-driven occurrence of the spontaneous electric polarization at a reasonably high temperature (T ) and an exchange bias (EB) effect below the antiferromagnetic (AFM) Néel temperature (T N ) are revealed in ZnFe 2 O 4 . We observe the magnetic memory effect, suggesting a cooperative glassy magnetic state below T N . The phase separation between the long-range AFM and the glassy magnetic component leads to the EB effect below T N . The synchrotron diffraction studies confirm a structural transition to a polar R3m structure from the cubic spinel structure, involving a strong rhombohedral distortion. This distortion correlates with the occurrence of the spontaneous electric polarization (P) below ∼110 K (T FE1 ), which is accompanied by a short-range order (SRO). The P-value enhances further due to an additional rhombohedral distortion below T N . A considerable magnetoelectric (ME) coupling is detected below T FE1 . The increase of P is ∼7.2% for 5 T at the liquid nitrogen temperature. There has been a fundamental interest among the community in the unique result of the occurrence of ferroelectric (FE) order coexisting with SRO and having a significant ME coupling, which is accompanied by a strong rhombohedral structural distortion analogous to that observed in BiFeO 3 .

Physical, Psycho-social and Economic Burden of Chronic Obstructive Pulmonary Disease: A Hospital-Based Study in Kolkata, West Bengal, India

“…227) represents a polar structure, exhibiting the highest symmetry among the various structures considered. This finding aligns with the rhombohedral distortion-driven structural transition to R3m structure from F d 3m, which was associated with the observed FE order in ZnFe 2 O 4 [51]. A satisfactory Rietveld refinement of the diffraction pattern at 175 K, employing the R3m space group, is presented in Fig.…”

Structural correlation to ferroelectric order, non-Griffiths like phase and magnetocaloric effect in YbCrO4

“…The structural study attempts to extract knowledge from the crystallography and understanding origins of the different multifunctional properties of the system. The structural correlation to the electrical and magnetic properties has been recently found crucial in few systems, which provides rich consequences in solid state such as colossal magnetoresistance [1], giant magnetocaloric effect [2], Griffiths phase singularities [3], spontaneous ferroelectric order [4,5], multiferroic order [6]. In the current observation we report important structural correlations to the various unexplored multifunctional properties of YbCrO 4 .…”

“…The decrease in current with increasing H is consistent with the variation of P with H as shown in the inset of figure 3(f). It is interesting to point out that the ME coupling is observed below ∼ 90 K, which is much above the magnetic ordering temperature at 25 K. The dominant short-range ordering above the ferrimagnetic ordering associated with the progressive structural distortion below T F E may correlate the significant ME consequence at much higher temperature, as recently observed in few occasions [4,7,40,41,42].…”

Slow spin dynamics of cluster spin-glass spinel Zn(Fe 1−x Ru x )2O4: role of Jahn–Teller active spin-1/2 Cu2+ ions at B-sites

“…Moreover, Suzuki et al reported large magneto-capacitance (∼10% at 14 T) and magnetization coupled dielectric relaxation in polycrystalline ZFO [49]. These results are further supported by very recent observations on ferroelectric behaviour linked to the rhombohedral distortion (R3m space group) from the cubic structure, across 110 K, along with the glassy AFM character and magnetic memory effects below T N in addition to a weak exchange bias effect [50]. Nevertheless, the high field susceptibility data and neutron scattering measurements of single crystalline ZFO by Kamazawa et al reported the absence of long-range order and diffuse magnetic scattering around the nuclear Bragg peaks which disappear under the application of an external magnetic field of magnitude ∼30 kOe [51][52][53].…”