One-dimensional anisotropic Heisenberg model in the transverse magnetic field |
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Authors: | D. V. Dmitriev V. Ya. Krivnov A. A. Ovchinnikov A. Langari |
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Affiliation: | (1) Joint Institute of Chemical Physics, Russian Academy of Sciences, Moscow, 117977, Russia;(2) Max-Planck-Institut für Physik Komplexer Systeme, 01187 Dresden, Germany;(3) Institute for Advanced Studies in Basic Sciences, Zanjan, 45195-159, Iran |
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Abstract: | The one-dimensional spin-1/2 XXZ model in a transverse magnetic field is studied. It is shown that the field induces a gap in the spectrum of the model with the easy-plane anisotropy. Using conformal invariance, the field dependence of the gap is found at small fields. The ground state phase diagram is obtained. It contains four phases with the long-range order of different types and a disordered phase. These phases are separated by critical lines, where the gap and the long-range order vanish. Using scaling estimates, the mean-field approach, and numerical calculations in the vicinity of all critical lines, we find the critical exponents of the gap and the long-range order. It is shown that the transition line between the ordered and disordered phases belongs to the universality class of the transverse Ising model. |
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