Magnetization-resolved density of states and quasi-first order transition in the two-dimensional random bond Ising model: an entropic sampling study

Fuente: arXiv
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Autores principales: Liu, Yi, Wang, Ding, Wang, Xin, Yao, Dao-Xin, Tang, Lei-Han
Formato: Preprint
Publicado: 2025
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author Liu, Yi
Wang, Ding
Wang, Xin
Yao, Dao-Xin
Tang, Lei-Han
author_facet Liu, Yi
Wang, Ding
Wang, Xin
Yao, Dao-Xin
Tang, Lei-Han
contents Systems with quenched disorder possess complex energy landscapes that are challenging to explore under the conventional Monte Carlo method. In this work, we implement an efficient entropy sampling scheme for accurate computation of the entropy function in low-energy regions. The method is applied to the two-dimensional $\pm J$ random-bond Ising model, where frustration is controlled by the fraction $p$ of ferromagnetic bonds. We investigate the low-temperature paramagnetic--ferromagnetic phase boundary below the multicritical point at $T_N = 0.9530(4)$, $P_N = 0.89078(8)$, as well as the zero-temperature ferromagnetic--spin-glass transition. Finite-size scaling analysis reveals that the phase boundary for $T < T_N$ exhibits reentrant behavior. By analyzing the evolution of the magnetization-resolved density of states $g(E, M)$ and ground-state spin configurations against increasing frustration, we provide strong evidence that the zero-temperature transition is quasi-first order. Finite-size scaling conducted on the spin-glass side supports the validity of $β= 0$, with a correlation length exponent $ν= 1.50(8)$. Our results provide new insights into the nature of the ferromagnetic-to-spin-glass phase transition in an extensively degenerate ground state.
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publishDate 2025
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spellingShingle Magnetization-resolved density of states and quasi-first order transition in the two-dimensional random bond Ising model: an entropic sampling study
Liu, Yi
Wang, Ding
Wang, Xin
Yao, Dao-Xin
Tang, Lei-Han
Disordered Systems and Neural Networks
Statistical Mechanics
Systems with quenched disorder possess complex energy landscapes that are challenging to explore under the conventional Monte Carlo method. In this work, we implement an efficient entropy sampling scheme for accurate computation of the entropy function in low-energy regions. The method is applied to the two-dimensional $\pm J$ random-bond Ising model, where frustration is controlled by the fraction $p$ of ferromagnetic bonds. We investigate the low-temperature paramagnetic--ferromagnetic phase boundary below the multicritical point at $T_N = 0.9530(4)$, $P_N = 0.89078(8)$, as well as the zero-temperature ferromagnetic--spin-glass transition. Finite-size scaling analysis reveals that the phase boundary for $T < T_N$ exhibits reentrant behavior. By analyzing the evolution of the magnetization-resolved density of states $g(E, M)$ and ground-state spin configurations against increasing frustration, we provide strong evidence that the zero-temperature transition is quasi-first order. Finite-size scaling conducted on the spin-glass side supports the validity of $β= 0$, with a correlation length exponent $ν= 1.50(8)$. Our results provide new insights into the nature of the ferromagnetic-to-spin-glass phase transition in an extensively degenerate ground state.
title Magnetization-resolved density of states and quasi-first order transition in the two-dimensional random bond Ising model: an entropic sampling study
topic Disordered Systems and Neural Networks
Statistical Mechanics
url https://arxiv.org/abs/2505.04298