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Disorder-Induced Superfluidity in Hardcore Bosons in Two Dimensions

Ji-Woo Lee·Shailesh Chandrasekharan·Harold U. Baranger
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Abstract

We study the effect of disorder on hardcore bosons in two dimensions at the SU(2) symmetric ``Heisenberg point''. We obtain our results with quantum Monte Carlo simulations using the directed loop algorithm. In the absence of disorder, the system has no long-range order at finite temperature due to the enhanced symmetry. However, the introduction of a disordered potential, uniformly distributed from -D to D, induces a finite-temperature superfluid phase. In particular the diagonal correlation length ξdecreases but the superfluid order-parameter correlation function becomes a power-law. A non-monotonic finite-size behavior is noted and explained as arising due to ξ. We provide evidence that at long distances the effects of a weak disordered potential can be mimicked by an effective uniform potential with a root-mean-square value: mu_eff = D/sqrt{3}. For strong disorder, the system becomes a Bose glass insulator.

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Ji-Woo Lee, Shailesh Chandrasekharan, Harold U. Baranger. 2006-11-04. Disorder-Induced Superfluidity in Hardcore Bosons in Two Dimensions. https://arxiv.org/abs/cond-mat/0611109

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