Specific Heat of a Regenerator Material Er₃Ni

Abstract

Specific heat measurement was performed in the temperature range from 800 mK to 62 K on the regenerator material Er 3 Ni which is an antiferromagnet with a Néel temperature of 6.1 K and possesses a large volumetric heat capacity even at temperatures above T N . The magnetic contribution to the specific heat has been carefully divided into two parts, one of which is caused by entropy change due to the magnetic ordering and the other a contribution from higher energy level states (Schottky anomaly). The energy levels of the 4f electrons for Er 3+ were calculated using the point-charge model, and compared with the experimental data. The entropy change of the Schottky anomaly is large compared with that of magnetic ordering and important for the regenerator material.