Metamagnetic transition and reversible magnetocaloric effect in antiferromagnetic DyNiGa compound*

Rare-earth (R)-based materials with large reversible magnetocaloric effect (MCE) are attracting much attention as the promising candidates for low temperature magnetic refrigeration. In the present work, the magnetic properties and MCE of DyNiGa compound with TiNiSi-type orthorhombic structure are studied systematically. The DyNiGa undergoes a magnetic transition from antiferromagnetic (AFM) to paramagnetic state with Neel temperatureT(N)= 17 K. Meanwhile, it does not show thermal and magnetic hysteresis, revealing the perfect thermal and magnetic reversibility. Moreover, the AFM state can be induced into a ferromagnetic state by a relatively low field, and thus leading to a large reversible MCE,e.g., a maximum magnetic entropy change (-Delta S-M) of 10 J/kg.K is obtained at 18 K under a magnetic field change of 5 T. Consequently, the large MCE without thermal or magnetic hysteresis makes the DyNiGa a competitive candidate for magnetic refrigeration of hydrogen liquefaction.