Phase diagram of the novel triangular lattice antiferromagnet ErTa7O19

Ising-like triangular lattice antiferromagnets represent a promising avenue in the search for enigmatic quantum states of matter. Our previous studies have demonstrated that erbium heptatantalate, ErTa7O19, is a realization of such a system with intriguing magnetic properties. Recent single-crystal neutron diffraction measurements performed on the WISH instrument (RB2320281, RB 2420338) have revealed a realization of the puzzling spin supersolid state below TN = 100 mK in zero field. However, the experiments also revealed that this state is, surprisingly, unstable against melting at low temperatures when the magnetic order on cooling transforms into a short-range ordered state with stripe-like correlations. We propose additional neutron diffraction experiments to determine the nature of this state as well as to investigate its stability against the applied magnetic field, which is known to stabilize a long-range up-up-down order reflecting in the 1/3 magnetization plateau in this system at higher temperatures.