Magnetic field-induced transition in a quantum magnet described by the Quantum Dimer Model

TL;DR

This paper investigates how a magnetic field influences a gapped quantum magnet using the Quantum Dimer Model, revealing a transition to a spinon superfluid phase with Bose condensation, indicating a novel quantum critical point.

Contribution

It introduces a minimal model for spinon proliferation under magnetic fields and explores this transition on square and triangular lattices using numerical methods.

Findings

Spinons are fully polarized and Bose-condense above a critical field.

A novel quantum critical point characterized by a spinon superfluid density.

Contrasts with the traditional triplet condensation scenario.

Abstract

The effect of a magnetic field on a gapped quantum magnet is described within the framework of the Quantum Dimer Model. A minimal model describing the proliferation of itinerant spinons above a critical field is proposed and investigated by Lanczos exact diagonalizations and quantum Monte Carlo simulations. For both square and triangular lattices, it is shown that spinons are fully polarized and Bose-condense. This offers a novel scenario of a Quantum Critical Point in the dimer-liquid phase (triangular lattice) characterized by the continuous appearance of a spinon superfluid density, contrasting with the usual triplet condensation picture. The possible role of other spinon kinetic terms neglected in the model are discussed.