Impact of the crystal electric field on magnetocaloric properties of CsGd(MoO$_4$)$_2$

TL;DR

This study investigates the magnetocaloric effect in CsGd(MoO4)2 single crystals, revealing significant entropy changes at low temperatures and fields, with potential for magnetic refrigeration applications due to its stability and low hysteresis.

Contribution

The paper provides detailed analysis of crystal electric field effects on magnetocaloric properties, enabling extrapolation of MCE parameters and highlighting CsGd(MoO4)2's suitability for low-temperature magnetic refrigeration.

Findings

Maximum entropy change of 19.2 J/kgK at 1 T

Expected entropy change of 26.8 J/kgK at 7 T

No thermal hysteresis or eddy current losses

Abstract

Magnetocaloric effect (MCE) was investigated in the single crystal of CsGd(MoO$_4$)$_2$ in the temperature range from 2 to 30 K and fields up to 5 T applied along the easy and hard magnetic axis. The analysis of specific heat and magnetization provided the refinement of crystal electric field (CEF) parameters supporting the dominance of uniaxial symmetry. The knowledge of CEF energy levels enabled the extrapolation of MCE parameters outside the experimental region. Consequently, maximum values of the isothermal entropy change, $-\Delta S_{\rm M}$, in magnetic fields up to 5 T are expected to occur at temperatures between 1 and 2 K. While $-\Delta S_{\rm M}$ achieves 19.2 J/kgK already for the field 1 T, for the field change 7 T, maximal $-\Delta S_{\rm M}$ $\approx$ 26.8 J/kgK with a refrigerant capacity of 215 J/kg is expected. The absence of thermal hysteresis and the losses due to eddy currents as well as good chemical stability makes the compound CsGd(MoO$_4$)$_2$ attractive for magnetic refrigeration at low temperatures. The possibilities of further enhancement of MCE parameters are discussed.