Bond Disorder in Even-Leg Heisenberg Ladders

TL;DR

This paper investigates how random bond disorder affects the phase diagram of antiferromagnetic spin-1/2 Heisenberg ladders, revealing the emergence of Bose glass and Bose-Einstein condensate phases depending on impurity distribution.

Contribution

It provides a detailed analysis of the effects of bond impurities on the phases of even-leg Heisenberg ladders using Quantum Monte Carlo simulations, highlighting the conditions for Bose glass and BEC phases.

Findings

Bose glass phases occur in specific magnetic field regimes.

Local bond energy distribution depends on impurity concentration.

Phase diagram is significantly altered by random bond doping.

Abstract

Random bond disorder in antiferromagnetic spin-1/2 Heisenberg ladders is investigated using the Stochastic Series Expansion Quantum Monte Carlo method. We find that the effects of individual bond impurities vary strongly, depending on their position on legs and rungs. We initially focus on how the distribution of local bond energies depends on the impurity concentration. Then we study how the phase diagram of even-leg ladders is affected by random bond doping. We observe Bose glass phases in two regimes ($h' < h \lesssim h_{c1}$ and $h" < h <h_{c2}$) and a Bose-Einstein Condensate in-between. Their presence are discussed in the relation to the local bond energies.