Multicritical behavior of the fidelity susceptibility for the 2D quantum transverse-field XY model
Department of Physics, Faculty of Science, Okayama University,
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Received in final form: 6 June 2019
Published online: 5 August 2019
The two-dimensional quantum XY model with a transverse magnetic field was investigated with the exact diagonalization method. Upon turning on the magnetic field h and the XY -plane anisotropy η, there appear a variety of phase boundaries, which meet at the multicritical point (h, η) = (2, 0). We devote ourselves to the Ising-universality branch, placing an emphasis on the multicritical behavior. As a probe to detect the underlying phase transitions, we adopt the fidelity susceptibility χF. The fidelity susceptibility does not rely on any presumptions as to the order parameter involved. We made a finite-size-scaling analysis of χF for η = 1 (Ising limit), where a number of preceding results are available. Thereby, similar analyses with η scaled were carried out around the multicritical point. We found that the χF data are described by the crossover scaling theory. A comparison with the preceding studies of the multicriticality is made.
Key words: Statistical and Nonlinear Physics
© EDP Sciences / Società Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2019