Field-induced transition in the (formula presented) antiferromagnetic chain with single-ion anisotropy in a transverse magnetic field

The field-induced transition in one-dimensional (formula presented) Heisenberg antiferromagnets with single-ion anisotropy in the presence of a transverse magnetic field is obtained on the basis of the Schwinger-boson mean-field theory. The behaviors of the specific heat and susceptibility as functions of temperature as well as the applied transverse field are explored, which are found to be different from the results obtained under a longitudinal field. The anomalies of the specific heat at low temperatures, which might be indicative of a field-induced transition from a Luttinger liquid phase to an ordered phase, are explicitly uncovered under the transverse field. A schematic phase diagram is proposed. The theoretical results are compared with experimental observations.