Hydrostatic pressure modulated spin-reorientation transition and magnetocaloric effect in PrGa compound

Abstract

The effect of hydrostatic pressure on the spin-reorientation transition and magnetocaloric effect in PrGa compound has been experimentally investigated. Because of the significant change of lattice parameter along with the spin reorientation, hydrostatic pressure can largely shift the spin reorientation temperature TSR from 28 K down to 16 K under 1.14 GPa, while magnetic transition at TC∼37 K hardly changes. Although the maximum entropy change ΔSM for a magnetic field change of 0–5T decreases from 9.2 J/kg K to 5.8 J/kg K as a pressure of 1.14 GPa was applied, an asymmetric broadening of ΔSM with magnetic field occurs due to the widening of metamagnetic transition window caused by pressure. As a result, a plateau develops on the ΔSM-T curve, and 10% improvement of effective refrigerant capacity RCeff has been achieved. The origin can be ascribed to the significant impact of the pressure on the lattice and crystal field interaction, which not only strengthens the first-order nature of the spin reorientation transition but also enlarges the distance between TSR and TC and broadens the temperature window of metamagnetic transition involving the specific spin alignment. The tunable TSR and enhanced RCeff by pressure in PrGa demonstrate that the compound can be useful in developing multi-field driven refrigeration technique.