Evidence of a first-order magnetic transition in HoPtSn

Single crystals of HoPtSn and its nonmagnetic analog LuPtSn are grown by flux method. They crystallize in the ${\mathrm{Fe}}₂\mathrm{P}$-type hexagonal structure with a distorted kagome lattice of rare-earth ions. Magnetic susceptibility measurements confirm that HoPtSn exhibits two antiferromagnetic transitions at 7.3 and 2.4 K, consistent with previous neutron-diffraction studies. Our detailed magnetic and electrical studies indicate that the transition at 2.4 K is a first-order magnetic transition, which is supported by the hysteresis loops observed in the temperature-dependent magnetic susceptibility and resistivity curves. In the case of $H||c$, the magnetic states of HoPtSn are sensitive to applied magnetic fields. The first-order magnetic transition can also be induced by magnetic fields, which is evidenced by the hysteresis loops observed from the isothermal magnetization and magnetoresistance curves. The magnetic phase diagram is depicted for the case of $H||c$. In the case of $H\ensuremath{\perp}c$, the antiferromagnetic transitions are relatively robust against magnetic fields up to 9 T.