Large Magnetocaloric effect and magnetic phase transitions in Nd${}_2$NiMnO${}_6$

Abstract

We present combined experimental and theoretical investigations on the magnetic and magnetocaloric behavior of Nd${}_2$NiMnO${}_6$. The relative cooling power (RCP) which quantifies the usefulness of a magnetocaloric (MC) material is estimated to be $\approx 300$ J/Kg near the ferromagnetic transition at $T_C\approx 195$ K. This RCP is comparable to the best known MC materials. Additionally, the magnetic entropy change has a broad profile ($T_C-50\mathrm{K}<T<T_C+50\mathrm{K}$) leading to an enhancement in the working-range of temperatures for magnetocaloric based cooling. These features make Nd${}_2$NiMnO${}_6$ a superior magnetocaloric material compared for example, to the nonmagnetic counterpart Y${}_2$NiMnO${}_6$. We identify the mechanism for the enhanced RCP which can guide search for future MC materials.

4 pages, 4 figures + 1 supplementary figure