Magnetic properties and magnetocaloric effect in TmGa and HoGa single crystals

We studied the magnetic property, heat capacity, and magnetocaloric effect of TmGa and HoGa single crystals. The observed magnetizations at three principal crystallographic axes display clear magnetic anisotropy, indicating an easy magnetic direction at the a-axis for TmGa and c-axis for HoGa. The measured specific heat of TmGa revealed the Curie temperature of 15 K and spin-reorientation temperatures at about 12.5 and 3.0 K respectively. Both samples exhibit giant reversible anisotropic magnetocaloric effect based on a second-order phase transition. Along the easy axis, the maximum value of magnetic entropy change for a magnetic field change of 0–5 T reaches 26.1 J kg−1 K−1 at 15 K and 14.9 J kg−1 K−1 at 65 K for TmGa and HoGa, respectively. The corresponding relative cooling powers are achieved to be 468 and 924 J kg−1. These values suggest the possibility of using these materials in magnetic refrigeration applications.

► The first experimental results of magnetic properties of TmGa are reported.
► Magnetocaloric effects of TmGa and HoGa are evaluated using single crystals.
► An obtained magnetic entropy change of TmGa was found to be about double that of HoGa.
► Estimated adiabatic temperature change of both compounds indicated high magnetocaloric potential.