Specific heat of Gd1−xErxGe1.5 as low-temperature-cryocooler regenerator materials

The specific heat C and the magnetization of Gd1−xErxGe1.5 were studied. From magnetization measurements, GdGe1.5 and ErGe1.5 showed antiferromagnetic ordering at the Néel temperatures TN of 29 K and 3 K, respectively. The jump in the C of Gd1−xErxGe1.5 due to the antiferromagnetic transition became small with increasing Er content, which is originated from the crystalline electric field effect and atomic randomness. Plots of C as a function of temperature for Gd1−xErxGe1.5 with x ≥ 0.5 exhibited a peak at temperatures below 15 K. These results suggest that TN could be controlled by substituting Er for Gd.