Ferromagnetic Eu<sub>2</sub>SiO<sub>4</sub> Compound with a Record Low-Field Magnetocaloric Effect and Excellent Thermal Conductivity Near Liquid Helium Temperature
Zhaojun Mo, Jiaxin Jiang, Tian Lu, Huicai Xie, Yan Li, Xinqi Zheng, Lei Zhang, Xinqiang Gao, Zhenxing Li, Guodong Liu, Lingwei Li, Jun Shen
Abstract
Researchers in the field of magnetic refrigeration have recently been chronically committed to the development of magnetic refrigeration materials with a large magnetocaloric effect (MCE) at low magnetic fields. In practice, a brilliant magnetic refrigeration material should not only exhibit a large MCE but also have excellent thermal properties. Therefore, pursuing such an ideal combination in materials becomes a necessity to realize the application of magnetic refrigeration. In this work, a good combination of MCE and thermal properties is presented in the ferromagnetic Eu 2 SiO 4 compound. The maximum magnetic entropy change (−Δ S M max ) reaches an impressive value of 21.6 J·kg –1 ·K –1 under a magnetic field change of 0–1 T, creating a new record for materials in the liquid helium temperature range. Heat capacity data show that the peak value of specific heat reaches 107.9 J·kg –1 ·K –1 near the liquid helium temperature. In addition, this compound exhibits excellent thermal conductivity, with a considerable value of 1.52 W·m –1 ·K –1 at 4.2 K, which surpasses most oxides and is comparable to that of the commercial regenerative material HoCu 2 . Remarkable magnetocaloric parameters and thermal properties enable Eu 2 SiO 4 to be a promising cryogenic magnetic refrigerant. The magnetic refrigeration experiments further prove it to be a brilliant magnetic refrigerant operating in the liquid helium temperature range.