Tuning magnetocaloric effect of Ho1-xGdxNi2 and HoNi2-yCoy alloys around hydrogen liquefaction temperature

We show the giant magnetocaloric effect of HoNi2 compound can be tuned around hydrogen liquefaction temperature by substituting Ho with Gd and Ni with Co in Ho1-xGdxNi2-yCoy. While the Curie temperature of Ho1-xGdxNi2-yCoy can be tuned from 15 to 32 K originating from the lattice expansion of the cubic structure, giant entropy change of 22.0 J/kgK is retained near the hydrogen liquefaction temperature. A table-like entropy change observed in a broad temperature range of 20 to 32 K makes them promising as magnetocaloric materials for cryogenic magnetic refrigeration utilizing an Ericsson cycle. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.