2002 年 43 巻 1 号 p. 73-77
Magnetization of MnAs1−xSbx was measured as functions of temperature and magnetic field for 0≤x≤0.4. The entropy change caused by a magnetic field, ΔSmag, was estimated on the basis of the Maxwell relation. The ΔSmag for 0≤x≤0.3 in a field change of 5 T reaches 25–30 J/K kg, which exceeds that of other materials by a factor of 2–4. The substitution of Sb for As can tune the Curie temperature between 230 K and 315 K without any significant reduction of ΔSmag. The large ΔSmag originates in a paramagnetic to ferromagnetic transition induced by a magnetic field. These results indicate that MnAs1−xSbx is a promising material for a working substance in magnetic refrigeration near room temperature.
