Low-temperature phases of the pyrochlore compoundTb2Ti2O7

Abstract

Low-temperature magnetic states of the pyrochlore compound ${\mathrm{Tb}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ with a geometrical frustration have been determined by measuring the specific heat, the susceptibility, and the residual magnetization of single-crystal samples. The moments of the lowest doublet of the ${\mathrm{Tb}}^{3+}$ ions set into a short-range ordering below about 2 K and show a maximum of the specific heat at ${T}_{\mathrm{sr}}\ensuremath{\approx}0.7\mathrm{K}.$ At ${T}_{\mathrm{c}}=0.37\mathrm{K},$ we observed a sharp peak of the specific heat which suggests that the second-order transition occurs. The static and the ac susceptibilities show another transition into a spin-glass or cluster-glass state below ${T}_{\mathrm{g}}=0.2\mathrm{K}.$ In the temperature range between 1.5 and 0.2 K, a residual magnetization was observed. The time dependencies of the residual magnetization and the dissipation of the ac susceptibility suggest existence of metastable states with a distribution of the relaxation times.