首页|Critical behavior of the Ashkin-Teller model with a line defect: Towards reconciliation between numerical and analytical results
Critical behavior of the Ashkin-Teller model with a line defect: Towards reconciliation between numerical and analytical results
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NSTL
Elsevier
We study magnetic critical behavior in the two-dimensional Ashkin-Teller model with an asymmetric defect line. This system is represented by two Ising lattices of spins sigma and tau interacting through a four-spin coupling epsilon. In addition, the couplings between sigma-spins are modified along a particular line, whereas couplings between tau-spins are kept unaltered. This problem has been previously considered by means of analytical field-theoretical methods and by numerical techniques, with contradictory results. For epsilon > 0 field-theoretical calculations give a magnetic critical exponent corresponding to sigma-spins which depends on the defect strength only (it is independent of epsilon), while tau-spins magnetization decay with the universal Ising value 1/8. On the contrary, numerical computations based on density matrix renormalization (DMRG) give, for epsilon > 0 similar scaling behaviors for sigma and tau spins, which depend on both epsilon and defect intensity. In this paper we revisit the problem by performing a direct Monte Carlo simulation. Our results are in good agreement with DMRG computations. By reexamining the field-theoretical approach, we show how numerical and analytical results can be reconciled when a more general regularization prescription is adopted. (C) 2022 Elsevier B.V. All rights reserved.
NSTL
Elsevier
