Large anisotropic magnetocaloric effect in ferromagnetic semimetal PrAlSi

We report on the large anisotropic magnetocaloric effect of PrAlSi, a ferromagnetic semimetal of current interest with a probable topologically nontrivial electronic structure. The maximum magnetic entropy change amounts to $−ΔSM=22.6J/kgK$ near the Curie temperature $TC=17.8K$ under a magnetic field change of $μ0ΔH=5T$ along the magnetic easy $c$ axis. A highly relevant feature is the small crystalline electric field splitting of the $Pr3+$ (⁠$J=4$⁠) multiplet, which appears to be comparable with the effective exchange interaction in the magnetic ordering. This leads to the full saturation moment of the $Pr3+$ ion in small fields and an accumulation of magnetic entropy in the vicinity of the magnetic ordering. The weakly first-order nature of the ferromagnetic transition and the subsequent reentrant spin-glass transitions below $TC$ are features further enhancing the magnetocaloric effect. Given the strong magnetic anisotropy, a large rotating magnetocaloric effect becomes achievable in this material.