The effects of magnetic field on thermodynamic properties of alternating Heisenberg chain

We study the effects of longitudinal magnetic field and temperature on the thermodynamic properties of one dimensional alternating Heisenberg antiferromagnet on the chain in the presence of dimerization parameter. In particular, the temperature dependence of specific heat have been investigated for various dimerization parameter and magnetic field strength in the model Hamiltonian. Using a hard core bosonic representation, the behaviors of thermodynamic properties have been studied by means of excitation spectrum of mapped bosonic gas. The effect of dimerization parameter, as the ratio between two types of exchange constants, on thermodynamic properties has also been studied via the bosonic model by Green's function approach. Furthermore we have studied the magnetic field dependence of specific heat and magnetization for various dimerization parameters. At low temperatures, the specific heat is found to be monotonically increasing with temperature for magnetic fields in the gapped field induced phase region. We have found the magnetic field dependence of specific heat shows a monotonic decreasing behavior for various dimerization parameter due to increase of energy gap in the excitation spectrum. Also we have studied the dependence of magnetization on magnetic field for different dimerization parameters.