Bistability and relaxor ferrimagnetism in off-stoichiometric NiCrO3

NiCrO3 has been proposed as a likely candidate for antiferromagnetic half metallic behaviour. A sample prepared at high pressure adopts the corundum structure with Ni/Cr cation disorder, and is found to have off-stoichiometric composition Ni0.80Cr1.20O3. This material shows complex local magnetic ordering phenomena at temperatures below 120 K but without any long range spin order observed by neutron diffraction. The transition to local ferrimagnetism occurs at 50-100 K, with two distinct regimes at T-C1 = 95 and T-C2 = 53 K evidencing electronic phase separation driven by variations in local composition. At low temperature the system undergoes a further transition at T-C3 = 22 K, assigned to potential freezing of a cluster glass-like state, that results in a substantial increase in magnetic anisotropy. Ni0.80Cr1.20O3 is a bistable relaxor ferrimagnet where magnetic properties are linked to the lattice strain manifold that is determined by the peculiarities in the local chemical composition. (C) 2017 Elsevier B.V. All rights reserved.