Magnetocaloric behavior in a spinel high-entropy oxide with magnetic cations distributed across A and B sites

Abstract

Magnetocaloric effect and relative cooling power of the high-entropy oxide (Ni${}_{0.2}$Mg${}_{0.2}$Co${}_{0.2}$Cu${}_{0.2}$Zn${}_{0.2}$)(Mn${}_{0.666}$Fe${}_{0.666}$Cr${}_{0.666}$)O${}_4$ have been systematically investigated. This material crystallizes in a cubic structure and undergoes a ferrimagnetic to paramagnetic transition. The maximum magnetic entropy change $\Delta$ S${}_{max}$ and relative cooling power were calculated for a field change from 100 Oe to 20 kOe, yielding values of 0.522 J/kg K and a consistently high RCP over a broad temperature range, respectively. The scaling approach near the transition temperature to study the behavior of magnetic entropy change $\Delta$ S${}_M$(T,H) revealed that, under high magnetic fields, the $\Delta$ S${}_M$(T,H) curves collapse into a single universal curve independent of temperature or external field. The theoretical model indicates that electron–electron interactions, magnetoelastic coupling, and electron–phonon scattering are crucial factors in determining the magnetocaloric effect of the system. These findings provide valuable insights into the potential of high-entropy oxides for solid-state cooling applications and open new avenues for exploring magnetocaloric properties.