Structural, magnetic, and magnetothermal properties of R2Co2Al (R = Tb, and Dy) compounds

The Tb2Co2Al and Dy2Co2Al alloys prepared in this study consist of 2:2:1 and 1:1:1 phases, which were identified by using the powder x-ray diffraction and scanning electron microscopy techniques. Considerable thermomagnetic irreversibility between the zero field cooled and field cooling magnetization were observed in the two alloys because of the energy barriers needed to overcome the alignment of domains. Remarkable intrinsic coercivity and remanence at temperatures close to absolute zero were also observed. The maximum magnetic entropy changes of the Tb2Co2Al and Dy2Co2Al alloys are 6.4 J/kg K and 10.6 J/kg K, respectively, with a field change from 0 to 50 kOe. The low magnetic entropy changes result from the low magnetization of the alloys even with a 50 kOe of applied field.

Research Highlights
► Two-phase structure was observed in the heat treated R2Co2Al (R = Tb, and Dy) alloys.
► Considerable irreversibility was observed between the ZFC and FC magnetization.
► Intrinsic, remarkable coercivity and remanence were also observed.
► Relatively low magnetic entropy changes were obtained and reasons are given.