Magnetic properties and magnetocaloric effect in RE ₅₅Co₃₀Al₁₀Si₅ (RE = Er and Tm) amorphous ribbons

The magnetic and magnetocaloric effects (MCE) of the amorphous RE ₅₅Co₃₀Al₁₀Si₅ (RE = Er and Tm) ribbons were systematically investigated in this paper. Compounds with R = Er and Tm undergo a second-order magnetic phase transition from ferromagnetic (FM) to paramagnetic (PM) around Curie temperature T _C ∼ 9.3 K and 3 K, respectively. For Er₅₅Co₃₀Al₁₀Si₅ compound, an obvious magnetic hysteresis and thermal hysteresis were observed at low field below 6 K, possibly due to spin-glass behavior. Under the field change of 0 T-5 T, the maximum values of magnetic entropy change ( − Δ S M max ) reach as high as 15.6 J/kg⋅K and 15.7 J/kg⋅K for Er₅₅Co₃₀Al₁₀Si₅ and Tm₅₅Co₃₀Al₁₀Si₅ compounds, corresponding refrigerant capacity (RC) values are estimated as 303 J/kg and 189 J/kg, respectively. The large MCE makes amorphous RE ₅₅Co₃₀Al₁₀Si₅ (RE = Er and Tm) alloys become very attractive magnetic refrigeration materials in the low-temperature region.