Field-induced quantum phase transition in the quasi 1D XY-like antiferromagnet Cs2CoCl4

Abstract

We explore the magnetic excitations as a function of applied field in the quasi 1D s=12 XY-like magnet Cs2CoCl4. A transition from spin–flop antiferromagnetic order to a quantum paramagnet occurs at the critical field BC=2.15T and fields higher than 2.5T fully align the spins along the field. In the spin–flop phase gapped scattering continua dominate, identified with the creation of pairs of quantum domain walls. In the saturated phase sharp peaks are observed, as expected for magnons in a ferromagnetically ordered ground state.