Tuning phase transitions and optimization of the magnetocaloric effect in Ho(Co<sub>1–</sub><sub><italic>x</italic></sub>Mn<sub><italic>x</italic></sub>)<sub>2</sub> alloys

Abstract

<p indent="0mm">In magnetic refrigerants, tuning the materials to the first-order/second-order borderline is expected to equip the material with the advantages of the first- and second-order transitions. In this work, we performed a systematic study on the nature of the phase transition, the magnetic entropy change, and the hysteresis loss in the Mn-doped Ho(Co_1–_{<italic>x</italic>}Mn_{<italic>x</italic>})₂ alloys. We found that at <italic>x</italic> = 0.02, the material was close to the borderline of the first-order/second-order transition and exhibited a large magnetocaloric effect along with a small hysteresis loss. At <italic>x</italic>&gt;0.02, the phase transition in the sample became a second-order type, and the magnetocaloric effect was greatly reduced. These results indicate that tuning the nature of phase transition in the RCo₂-based magnetic material is an effective strategy of optimizing its magnetocaloric performance.