The Valence Bond Glass phase

TL;DR

This paper introduces the Valence Bond Glass phase, a novel disordered state arising from magnetic frustration and quantum fluctuations, characterized by critical correlations without magnetic order or a true gap.

Contribution

It demonstrates the existence of a Valence Bond Glass phase in the Hubbard-Heisenberg model on a Bethe lattice using large N techniques, expanding understanding of disordered quantum phases.

Findings

Identification of a new Valence Bond Glass phase

Phase diagram including Fermi liquid, dimer, and valence bond glass phases

Absence of a true gap with presence of pseudo-gap and critical correlations

Abstract

We show that a new glassy phase can emerge in presence of strong magnetic frustration and quantum fluctuations. It is a Valence Bond Glass. We study its properties solving the Hubbard-Heisenberg model on a Bethe lattice within the large $N$ limit introduced by Affleck and Marston. We work out the phase diagram that contains Fermi liquid, dimer and valence bond glass phases. This new glassy phase has no electronic or spin gap (although a pseudo-gap is observed), it is characterized by long-range critical valence bond correlations and is not related to any magnetic ordering. As a consequence it is quite different from both valence bond crystals and spin glasses.