Emergent room-temperature ferroelectricity in spark-plasma sintered DyCrO and LaCrO
arXiv:2305.11546 · doi:10.1103/PhysRevB.107.214104
Abstract
Identification of novel multiferroic materials with high-ordering temperatures remains at the forefront of condensed matter physics research. In this regard, the antiferromagnetic RCrO compounds (like GdCrO) constitute a promising class of multiferroic compounds, which, however, mostly become ferroelectric concomitant with the antiferromagnetic ordering much below room-temperature, arising from a subtle competition between the ferroelectric off-centering mode and a non-polar antiferrodistortive rotation mode that inhibits ferroelectricity. Recently, room-temperature ferroelectricity of structural origin, arising from off-centering displacements of R and Cr ions, has been identified in spark-plasma sintered GdCrO [Suryakanta Mishra et al., Phys. Rev. B 104, L180101 (2021)]. Interestingly, some of the experimentally observed non-ferroelectric RCrO compounds have been theoretically predicted to host similar ferroelectric instabilities. Here, we have identified two such non-ferroelectric RCrO3 compounds, one DyCrO (which is reported as a quantum paraelectric) and another LaCrO (which is paraelectric), and using a modified synthesis protocol involving spark-plasma-sintering (SPS), we have been successful in engineering an intrinsic room-temperature ferroelectricity in the paramagnetic state, driven by noncentrosymmetric structural phase in both SPS sintered DyCrO and LaCrO, in contrast to room-temperature paraelectricity in solid-state synthesized DyCrO and LaCrO. While the ferroelectricity in SPS-prepared DyCrO and LaCrO is stable at room-temperature, it undergoes an irreversible transition from a ferroelectric (Pna2) phase to a paraelectric (Pbnm) phase at 440 K. Significantly, SPS-sintered LaCrO, which undergoes antiferromagnetic ordering at 290 K, emerges as a promising near room-temperature multiferroic material.
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