First {{Order Metamagnetic Transition}} in ${\mathrm{Ho}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ {{Observed}} by {{Vibrating Coil Magnetometry}} at {{Milli}}-{{Kelvin Temperatures}}

We report vibrating coil magnetometry of the spin-ice system Ho2Ti2O7 down to $\sim$0.04 K for magnetic fields up to 5 T applied parallel to the [111] axis. History-dependent behavior emerges below T$∗$0$\sim$0.6 K near zero magnetic field, in common with other spin-ice compounds. In large magnetic fields, we observe a magnetization plateau followed by a hysteretic metamagnetic transition. The temperature dependence of the coercive fields as well as the susceptibility calculated from the magnetization identify the metamagnetic transition as a line of first order transitions terminating in a critical end point at T$∗$m$\simeq$0.37 K, Bm$\simeq$1.5 T. The metamagnetic transition in Ho2Ti2O7 is strongly reminiscent of that observed in Dy2Ti2O7, suggestive of a general feature of the spin ices.     «

We report vibrating coil magnetometry of the spin-ice system Ho2Ti2O7 down to $\sim$0.04 K for magnetic fields up to 5 T applied parallel to the [111] axis. History-dependent behavior emerges below T$∗$0$\sim$0.6 K near zero magnetic field, in common with other spin-ice compounds. In large magnetic fields, we observe a magnetization plateau followed by a hysteretic metamagnetic transition. The temperature dependence of the coercive fields as well as the susceptibility calculated from the magneti...     »