Interplay of spin and orbital ordering in a frustrated spinel chromite

Abstract

Abstract Geometric Spin Frustration, when sufficiently strong, provides a platform for novel spin textures with emergent phenomena, such as ferroelectricity. This article investigates NiCr2O4, a spinel chromite co-hosting the frustration of Cr3+ spins with orbital frustration of Ni2+ ions, with the latter expected to eradicate the spin frustration by lowering lattice symmetry. Detailed experiments unveil an intriguing reentrant-spin-glass-like behavior alongside the previously known canted ferrimagnetism. Our analysis focuses on the ordering of Cr3+ spins at two distinct sublattices, with one contributing to canted ferrimagnetism, while the other exhibits a local ↑↑↓↓ (spin-frustrated) texture, potentially inducing spin-glass behavior. Density functional theory calculations corroborate the experimental findings, establishing ↑↑↓↓ as the ground state of NiCr2O4. This study presents new prospects for ferroelectricity driven by exchange striction in orbitally ordered spinel chromites.