The origin of large low-temperature specific heat in an Er–Cu–Ga magnetic regenerator material

In this work, the low-temperature volumetric specific heat, magnetic structure, and phase transition of the ErCu0.92Ga0.08 intermetallic alloy are investigated. It is found that ErCu0.92Ga0.08 exhibits a maximum specific heat of 0.96 J/(K cm3) at 15.9 K, which surpasses that of a commercial Pb material used as a regenerator in cryocoolers. Two successive magnetic phase transitions, namely, antiferromagnetic-to-paramagnetic transition and antiferromagnetic spin-reorientation transition, are observed in ErCu0.92Ga0.08 via Neutron Powder Diffraction. The anomalous specific heat behavior can be ascribed to the spin-reorientation transition. Based on the findings, it is believed that ErCu0.92Ga0.08 can be a new magnetic regenerator material for low-temperature cryocoolers.