Bose and Mott Glass Phases in Dimerized Quantum Antiferromagnets

TL;DR

This paper investigates how disorder affects dimerized quantum antiferromagnets in a magnetic field, revealing complex glass phases including a rare Mott glass, using advanced theoretical methods.

Contribution

It introduces a novel analytic description of Mott and Bose glass phases in disordered quantum antiferromagnets, emphasizing the importance of replica symmetry breaking.

Findings

Transition from Mott insulator to Bose glass away from Mott lobe tips

Identification of a rare Mott glass phase with suppressed compressibility

Demonstration that glass phase formation involves rich physics beyond weak localization

Abstract

We examine the effects of disorder on dimerized quantum antiferromagnets in a magnetic field, using the mapping to a lattice gas of hard-core bosons with finite-range interactions. Combining a strong-coupling expansion, the replica method, and a one-loop renormalization group analysis, we investigate the nature of the glass phases formed. We find that away from the tips of the Mott lobes, the transition is from a Mott insulator to a compressible Bose glass, however the compressibility at the tips is strongly suppressed. We identify this finding with the presence of a rare Mott glass phase not previously described by any analytic theory for this model and demonstrate that the inclusion of replica symmetry breaking is vital to correctly describe the glassy phases. This result suggests that the formation of Bose and Mott glass phases is not simply a weak localization phenomenon but is indicative of much richer physics. We discuss our results in the context of both ultracold atomic gases and spin-dimer materials.