Barocaloric and magnetocaloric effects in (MnNiSi)_(1-x)(FeCoGe)_x

摘要

(MnNiSi)_(1-x)(FeCoGe)_x undergoes a magnetostructural phase transition near room temperature that is acutely sensitive to applied hydrostatic pressure, which presents as a marked shift in the martensitic transition temperature (T_M) by about -7.5 K/kbar. The magnetostructural transition can therefore be induced by applied hydrostatic pressure or by magnetic field. The barocaloric and magnetocaloric effects were measured across T_M (for the sample with x = 0.38), and the corresponding entropy changes were +74J/kgK (P = 2.7kbar) and -58J/kgK (μ_0H=5T), respectively. It was observed that the transition entropy change increases with pressure, which results in an enhancement of the barocaloric effect. Our measurements show that the transformed phase fraction associated with magnetostructural transition does not depend on pressure and, therefore, this enhancement cannot be attributed to a pressure-assisted completion of the phase transformation.