Room temperature ferrimagnetism, magnetodielectric and exchange bias effect in CoFeRhO4

Geometrically frustrated structures, combined with competing exchange interactions that have different magnitudes, are known ingredients for achieving exotic properties. Herein, we studied detailed structural, magnetic, thermal (specific heat), magnetodielectric, and magnetic exchange bias properties of a mixed $3d\text{\ensuremath{-}}4d$ spinel oxide with composition ${\mathrm{CoFeRhO}}_{4}$. Detailed magnetization, heat capacity, and neutron powder diffraction studies highlight long-range ferrimagnetic ordering with an onset at 355 K. The magnetic structure is established using a ferrimagnetic model (collinear type) that has a propagation vector $k=0$, 0, and 0. The magnetodielectric effect appears below the magnetic ordering temperature, and the exchange bias (EB) effect is observed in field-cooled conditions below 355 K. The magnetodielectric coupling in ${\mathrm{CoFeRhO}}_{4}$ originates due to the frustration in the structure, collinear ferrimagnetic ordering, and uncompensated magnetic moments. The unidirectional anisotropy resulting from the uncompensated magnetic moments causes the room-temperature exchange bias effect. Remarkably, the appearance of technologically important properties (ferromagnetism, magnetodielectric effect, and EB) at room temperature in ${\mathrm{CoFeRhO}}_{4}$ indicates its potential use in sensors or spintronics.