Low Temperature Behavior of a Two-Dimensional Quantum Antiferromagnet

We analyze the two-dimensional antiferromagnet with a quantum disordered ground state and a gap to bosonic excitations with finite spin. The zero temperature (T = 0) quantum phase transition is studied, and the finite temperature effects are also considered in the low temperature approximation of the Renormalization Group Method. The violation of the universality expected for d = 2 system has been shown to be logarithmic for T = 0 and T 0. We showed that chemical potential and the ground state energy depends on the interaction parameters at T = 0 and T 0. but this dependence is logarithmic.