Evolution of magnetic properties and magnetocaloric effect in TmNi1−xCuxAl (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) compounds
The magnetic and magnetocaloric properties of TmNi1-xCuxAl (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) compounds have been investigated. With the substitution of Ni by Cu, the Tm-magnetic moment rotates its direction from basal plane to the c-axis and finally becomes canted antiferromagnetism structure with larger projected moments along the c-axis near Tord. Furthermore, large reversible magnetocaloric effects have been observed in TmNi1-xCuxAl compounds around Tord, with no thermal hysteresis and magnetic hysteresis loss. The values of −ΔSMmax and refrigerant capacity are greatly improved when the part of Ni was superseded by Cu. In particular, under the magnetic field change of 2 T, a large −ΔSMmax of TmNi0.7Cu0.3Al (10.7 J/kg K) is almost twice that of TmNiAl (5.5 J/kg K) and 17.2 J/kg K for TmCuAl around 4 K. The present results indicate that TmNi1-xCuxAl (x ≥ 0.3) compounds could be considered as good candidate materials for low-temperature and low-field magnetic refrigerant.