Magnetocaloric properties of single-crystalline Eu$_5$In$_2$Sb$_6$

Abstract

The magnetocaloric effect (MCE) in single-crystalline Eu$_5$In$_2$Sb$_6$ was studied over broad temperature ranges and magnetic field intervals, with the magnetic field oriented parallel and perpendicular to the crystallographic $\textit{c}$-axis in the orthorhombic Ca$_5$Ga$_2$As$_6$-type unit cell of the crystals. The compound is an antiferromagnetic insulator with two subsequent magnetic phase transitions at $T_{N1} \approx$ 14.0 K and $T_{N2} \approx$ 7.1 K. The compound was found to exhibit both normal and inverse MCE. Furthermore, due to substantial magnetic anisotropy, it also exhibits a rotational MCE. For conventional MCE, the maximum value of the isothermal entropy change $\Delta S_m$ is -4.7(1) J kg$^{-1}$ K$^{-1}$ at 15(1) K for a magnetic field change of 5 T, independent of the field direction. The relative cooling power (RCP) is also almost identical for both directions, and equals 81(1) J kg$^{-1}$ for a magnetic field change of 5 T. The most significant rotational MCE was observed at about 11 K, with a maximum $\Delta S_R$ value of 2.4(1) J kg$^{-1}$ K$^{-1}$ and RCP = 17.5(6) J kg$^{-1}$ for a magnetic field change of 4 T.