Crystal electric field measurement of the Kosterlitz-Thouless phase candidate TmZn2GaO5 without structural disorder

An emergent U(1) symmetry and the Kosterlitz-Thouless phase have been proposed in the transverse field Ising model on the antiferromagnetically coupled triangular lattice. This was initially thought to be realized in TmMgGaO4, which however turned out elusive as the Mg/Ga disorder induces extra complexity.
We have newly synthesized TmZn2GaO5 where Tm3+ ions reside on the perfect triangular lattice but with no Mg/Ga disorder. It is promising to yield unambiguous result for the long persuit KT phase in 2D magnets. As the first step, we propose to perform inelastic neutron scattering experiment to measure the CEF levels to construct the effective spin model.