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arXiv · 0809.1987

Thermodynamic behavior of the XXZ Heisenberg s=1/2 chain around the factorizing magnetic field

J. Abouie·A. Langari·M. Siahatgar
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Abstract

We have investigated the zero and finite temperature behaviors of the anisotropic antiferromagnetic Heisenberg XXZ spin-1/2 chain in the presence of a transverse magnetic field (h). The attention is concentrated on an interval of magnetic field between the factorizing field (h_f) and the critical one (h_c). The model presents a spin-flop phase for 0<h<h_f with an energy scale which is defined by the long range antiferromagnetic order while it undergoes an entanglement phase transition at h=h_f. The entanglement estimators clearly show that the entanglement is lost exactly at h=h_f which justifies different quantum correlations on both sides of the factorizing field. As a consequence of zero entanglement (at h=h_f) the ground state is known exactly as a product of single particle states which is the starting point for initiating a spin wave theory. The linear spin wave theory is implemented to obtain the specific heat and thermal entanglement of the model in the interested region. A double peak structure is found in the specific heat around h=h_f which manifests the existence of two energy scales in the system as a result of two competing orders before the critical point. These results are confirmed by the low temperature Lanczos data which we have computed.

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J. Abouie, A. Langari, M. Siahatgar. 2010-04-23. Thermodynamic behavior of the XXZ Heisenberg s=1/2 chain around the factorizing magnetic field. https://doi.org/10.1088/0953-8984%2F22%2F21%2F216008

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