Thermal Properties of Rung Disordered Two-leg Quantum Spin Ladders: Quantum Monte Carlo Study

TL;DR

This study uses quantum Monte Carlo simulations to analyze how disorder affects the thermal properties of two-leg quantum spin ladders, revealing a unique temperature point and the impact of disorder on the spin gap.

Contribution

First comprehensive QMC analysis of disordered two-leg spin ladders, identifying a temperature point where specific heat is disorder-independent and quantifying disorder effects on the spin gap.

Findings

Existence of a temperature where specific heat is unaffected by disorder

Uniform susceptibility shows similar disorder-independent behavior

Spin gap decreases with increasing disorder, remaining above the clean limit

Abstract

A two-leg quenched random bond disordered antiferromagnetic spin$-1/2$ Heisenberg ladder system is investigated by means of stochastic series expansion (SSE) quantum Monte Carlo (QMC) method. Thermal properties of the uniform and staggered susceptibilities, the structure factor, the specific heat and the spin gap are calculated over a large number of random realizations in a wide range of disorder strength. According to our QMC simulation results, the considered system has a special temperature point at which the specific heat take the same value regardless of the strength of the disorder. Moreover, the uniform susceptibility is shown to display the same character except for a small difference in the location of the special point. Finally, the spin gap values are found to decrease with increasing disorder parameter and the smallest gap value found in this study is well above the weak coupling limit of the clean case.