Magneto-elastic coupling and magnetocaloric effect in hexagonal Mn-Fe-P-Si compounds

TL;DR

This study investigates the magneto-elastic coupling and magnetocaloric properties of Fe2P-based Mn-Fe-P-Si compounds, revealing large coupling effects and potential for efficient magnetic refrigeration.

Contribution

It uncovers the development of magneto-elastic coupling in the paramagnetic state and its impact on magnetic moments and entropy change in Mn-Fe-P-Si compounds.

Findings

Large magneto-elastic coupling develops in the paramagnetic state.

Discontinuous changes in lattice parameters occur at the magnetic transition.

Small hysteresis can be achieved with a giant magnetocaloric effect.

Abstract

Structural, magnetic and magnetocaloric properties of Fe2P-based Mn-Fe-P-Si compounds were investigated. The study reveals a large magneto-elastic coupling that starts to develop in the paramagnetic state and grows when the ferromagnetic transition temperature is approached. Based on the behavior of the magneto-elastic coupling, we show the thermal evolution of the magnetic moments. On cooling, magnetic moments on the tetrahedral site form and gradually increase in the paramagnetic state. At the magnetic ordering temperature the moments attain a much larger value in a discontinuous step. We also find that the hysteresis and magnetic entropy change are correlated with discontinuous changes in the lattice parameters at the transition temperature. Small hysteresis can be obtained while maintaining giant magnetocaloric effect.