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

TL;DR

This study investigates the magnetocaloric effect in single-crystalline Eu$_5$In$_2$Sb$_6$, revealing both normal and inverse effects, magnetic anisotropy, and potential for magnetic cooling applications at low temperatures.

Contribution

It provides the first detailed analysis of the magnetocaloric properties and anisotropy of Eu$_5$In$_2$Sb$_6$, including rotational effects and phase transitions.

Findings

Maximum isothermal entropy change of -4.7 J/kg·K at 15 K for 5 T

Significant rotational MCE with ΔS_R of 2.4 J/kg·K at 11 K

Relative cooling power of approximately 81 J/kg for 5 T field change

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.