Abstract
We report a ferroelectric order at K for , which carries an inverse spinel structure with a centrosymmetric structure at room temperature. The value of spontaneous electric polarization is considerably high as for 5 kV/cm poling field. The electric polarization decreases considerably () around the liquid-nitrogen temperature upon application of 50 kOe field, proposing a significant magnetoelectric coupling. The synchrotron diffraction studies confirm a structural transition at K to a noncentrosymmetric structure of space group. The occurrence of polar order is associated with an ordered occupancy of Ni and Fe atoms at the octahedral sites of the structure, instead of random occupancies at the octahedral site of the inverse spinel structure. The results propose that is a member in the type-II multiferroics.
- Received 4 December 2018
- Revised 19 March 2019
DOI:https://doi.org/10.1103/PhysRevB.99.144412
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