https://doi.org/10.1140/epjb/e2020-10264-5
Regular Article
Fidelity-susceptibility analysis of the honeycomb-lattice Ising antiferromagnet under the imaginary magnetic field
Department of Physics, Faculty of Science, Okayama University,
Okayama
700-8530, Japan
a e-mail: nisiyama@psun.phys.okayama-u.ac.jp
Received:
23
May
2020
Received in final form:
18
July
2020
Accepted:
29
July
2020
Published online: 14 September 2020
The honeycomb-lattice Ising antiferromagnet subjected to the imaginary magnetic field H = iθT∕2 with the “topological” angle θ and temperature T was investigated numerically. In order to treat such a complex-valued statistical weight, we employed the transfer-matrix method. As a probe to detect the order–disorder phase transition, we resort to an extended version of the fidelity F, which makes sense even for such a non-Hermitian transfer matrix. As a preliminary survey, for an intermediate value of θ, we investigated the phase transition via the fidelity susceptibility χF(θ). The fidelity susceptibility χF(θ) exhibits a notable signature for the criticality as compared to the ordinary quantifiers such as the magnetic susceptibility. Thereby, we analyze the end-point singularity of the order–disorder phase boundary at θ = π. We cast the χF(θ) data into the crossover-scaling formula with δθ = π − θ scaled carefully. Our result for the crossover exponent ϕ seems to differ from the mean-field and square-lattice values, suggesting that the lattice structure renders subtle influences as to the multi-criticality at θ = π.
Key words: Statistical and Nonlinear Physics
© EDP Sciences / Società Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020