Ferromagnetic Eu₂SiO₄ Compound with a Record Low-Field Magnetocaloric Effect and Excellent Thermal Conductivity Near...

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 Eu₂SiO₄ compound. The maximum magnetic entropy change (-ΔS_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 HoCu₂. Remarkable magnetocaloric parameters and thermal properties enable Eu₂SiO₄ 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.