Significant enhancement of magnetocaloric effects via tuning Curie temperature and magnetic anisotropy in rare-earth based compounds

Abstract

Magnetic refrigeration (MR) research has been increasingly focused on targeting operation temperatures as low as 4.4–20 K, which is of strategic significance for liquid helium and hydrogen in various activities such as aerospace and highly advanced industries. To date, despite most research has been aimed at obtaining MR materials with large magnetic entropy change and adiabatic temperature change, the optimizing operation temperature to target the cooling range for helium-hydrogen liquefaction is highly desirable and valuable. Here, the significant enhancement in magnetocaloric effects (MCEs) and magnetic materials operating in the temperature range of 4.4–20 K are achieved. The magnetic properties and MCEs of HoCuAl are manipulated by substituting Er or Tm atoms with the lower de Gennes factor and various magnetic anisotropy. The maximum magnetic entropy change ((−ΔSM)max) and refrigeration capacity (RC) under 0–5 T for Ho0.9Er0.1CuAl increases by 25.8 % and 39.8 % respectively compared with HoCuAl compound. Additionally, the critical role of Curie temperature and magnetic anisotropy in the significant enhancement of MCEs is confirmed by the systematic macroscopic physical analysis and neutron diffraction measurements. The excellent MCEs, suitable operation temperature, and free of hysteresis loss demonstrate the promising application prospect in liquefaction of helium-hydrogen.