Temperature dependence of the gap in the S = 1/2 antiferromagnetic chain in the presence of a staggered field

摘要

We calculate the temperature dependent energy gap in the magnetic excitation spectrum of the one-dimensional spin 1/2 antiferromagnetic Heisenberg model in the presence of a staggered magnetic field, using the phase Hamiltonian, a self consistent harmonic approximation, and the thermal-Green function technique.