Flux-induced strengthening of the magnetic couplings in a flat-band diamond chain

TL;DR

This paper demonstrates that Aharonov-Bohm flux can significantly enhance magnetic exchange couplings in flat-band diamond chains, affecting thermal conductivity and linking to quantum geometry, with implications for spintronics and quantum heat transport.

Contribution

It reveals how magnetic flux can strengthen magnetic couplings in flat-band systems, a novel effect with potential applications in quantum device control.

Findings

Aharonov-Bohm flux amplifies short-range magnetic couplings.

Flux-dependent decay length relates to quantum metric.

Enhanced thermal conductivity of magnons observed.

Abstract

The physics in flat bands has emerged as an essential field in condensed matter physics where a plethora of phenomena can be unveiled, such as anomalous transport properties, superconductivity dominated by quantum geometry or exotic topological phases. Our goal here is to show that even in magnetic systems, the presence of flat bands can give rise to unexpected features. More precisely, we address the impact of an Aharonov-Bohm (AB) flux on the exchange couplings in magnetic diamond chains. The most remarkable result is the significant amplification of magnetic couplings at short distances induced by the AB flux, leading to a considerable increase in the thermal conductivity of the magnons. We have also shown that the flux-dependent decaying length of the couplings is connected to the quantum metric of the flat bands. Our results could be of interest for the control of magnetic properties in spintronic devices and relevant for the heat transport by magnons at the nanoscale in quantum technologies.