Spin-Peierls phases in pyrochlore antiferromagnets

TL;DR

This paper explores how lattice distortions in pyrochlore antiferromagnets lead to spin-Peierls phases characterized by bond order without magnetic order, revealing diverse magnetic phases through theoretical analysis.

Contribution

It introduces a theoretical framework showing that lattice coupling induces spin-Peierls phases with bond order in pyrochlore antiferromagnets, expanding understanding of their magnetic behavior.

Findings

Pyrochlore lattice undergoes Jahn-Teller distortion due to lattice-magnetic coupling.

The system exhibits spin-Peierls phases with bond order but no spin order.

Multiple Neel phases, including collinear, coplanar, and noncoplanar, are identified.

Abstract

In the highly frustrated pyrochlore magnet spins form a lattice of corner sharing tetrahedra. We show that the tetrahedral ``molecule'' at the heart of this structure undergoes a Jahn-Teller distortion when lattice motion is coupled to the antiferromagnetism. We extend this analysis to the full pyrochlore lattice by means of Landau theory and argue that it should exhibit spin-Peierls phases with bond order but no spin order. We find a range of Neel phases, with collinear, coplanar and noncoplanar order. While collinear Neel phases are easiest to generate microscopically, we also exhibit an interaction that gives rise to a coplanar state instead.