Magnetic and magnetoresistive properties of cubic Laves phase HoAl$_2$ single crystal

We report the magnetization ($M$) and magnetoresistance (MR) results of HoAl$_2$ single crystals oriented along $<100>$ and $<110>$ directions. Although HoAl$_2$ has cubic Laves phase structure, a large anisotropy is observed in $M$ and MR results below Curie temperature ($T_C$) at 31.5 K. A satisfactory correlation between magnetic entropy change ($ΔS_M$) and MR could be established along $<110>$ direction and in $<100>$ direction except for the temperature ($T$) region, around which spin reorientation takes place. Large inverse magnetocaloric effect is observed at low-$T$ which is associated with the spin reorientation process in $<100>$ direction. A theoretical model based on Landau theory of phase transition can describe $T$-variation of -$ΔS_M$ for $T > T_C$.