Bond order wave instabilities in doped frustrated antiferromagnets: "Valence bond solids" at fractional filling

TL;DR

This paper investigates doped frustrated antiferromagnets, revealing a generic instability towards valence bond solid states at fractional filling, characterized by modulated bond strengths and broken lattice symmetries.

Contribution

It introduces a new class of valence bond solid states at fractional filling in doped frustrated antiferromagnets, extending the understanding of symmetry breaking in these systems.

Findings

Identification of a symmetry breaking instability at fractional filling

Observation of modulated bond strengths without lattice symmetry breaking

Generalization of valence bond solids to doped, fractional filling regimes

Abstract

We explore both analytically and numerically the properties of doped t-J models on a class of highly frustrated lattices, such as the kagome and the pyrochlore lattice. Focussing on a particular sign of the hopping integral and antiferromagnetic exchange, we find a generic symmetry breaking instability towards a twofold degenerate ground state at a fractional filling below half filling. These states show modulated bond strengths and only break lattice symmetries. They can be seen as a generalization of the well-known valence bond solid states to fractional filling.