Glass forming ability, magnetic properties and cryogenic magnetocaloric effects in RE60Co20Al20 (RE = Ho, Er, Tm) amorphous ribbons

Abstract The rare-earths (RE) based amorphous materials with large magnetocaloric (MC) effects and excellent glass forming ability (GFA) have been recognized as promising candidates for magnetic refrigeration (MR). In this work, the RE60Co20Al20 (RE = Ho, Er, Tm) amorphous ribbons were successfully fabricated and systematically determined with respect to the GFA, magnetic properties and MC effects. A second order magnetic phase transition (MPT) from ferromagnetic to paramagnetic (FM to PM) without noticeable field or thermal hysteresis has been observed around the Curie temperatures, TC ~ 22.3 K for Ho60Co20Al20, ~ 10.3 K for Er60Co20Al20, and ~ 5.0 K for Tm60Co20Al20, respectively. The MC parameters including the maximum magnetic entropy change ( | Δ S M max | ), temperature-averaged entropy change with 3 K lift [TEC (3 K)], and relative cooling powder/refrigerant capacity (RCP/RC) have been determined to check the MC performances, and the corresponding values are determined to be 14.16, 15.57 and 15.06 J/kgK, to be14.04, 15.38 and 14.78 J/kgK, and to be 625.0/478.7, 505.7/391.8 and 334.0/243.4 J/kg for Ho60Co20Al20, Er60Co20Al20 and Tm60Co20Al20 under the field change Δμ0H = 5 T, respectively. The present results indicate that RE60Co20Al20 (RE = Ho, Er, Tm) amorphous ribbons are considerable for cryogenic MR application.