Large magnetic refrigerant capacity of HoFe1−xCoxAl (x = 0, 0.3) compounds

Magnetic and magnetocaloric properties of HoFe 1− x Co x Al ( x = 0, 0.3) were investigated. Both HoFeAl and HoFe 0.7 Co 0.3 Al undergo a second-order ferromagnetic (FIM) to paramagnetic (PM) transition at Curie temperatures ( T C ) of 87 and 82 K, respectively. The magnetocaloric effect is improved by the introduction of Co in HoFeAl compound. For a field change from 0 to 5 T, the maximum values of magnetic entropy change (−Δ S M ) are 7.0 J·kg −1 ·K −1 for HoFeAl and 8.6 J·kg −1 ·K −1 for HoFe 0.7 Co 0.3 Al. In addition, the refrigerant capacity (RC) is enhanced largely from 416.2 J·kg −1 for HoFeAl to 561.9 J·kg −1 for HoFe 0.7 Co 0.3 Al. This large RC is attributed to the large Δ S M and the wide temperature span of Δ S M peak in HoFe 0.7 Co 0.3 Al compound. The physical mechanism of improvement in magnetocaloric effect by Co substitution in HoFeAl was also discussed in detail.