Long-lived magnetization in an atomic spin chain tuned to a diabolic point

TL;DR

This study demonstrates that tuning an atomic spin chain to a diabolic point significantly suppresses quantum tunneling of magnetization, leading to greatly increased magnetization lifetimes and advancing quantum magnet engineering.

Contribution

It reveals how precise tuning to diabolic points can control quantum tunneling effects in atomic spin chains, enabling longer magnetization stability.

Findings

Magnetization lifetimes increase by three orders of magnitude near diabolic points.

Local environment effects suppress quantum tunneling at diabolic points.

Multiple diabolic points can be engineered by adjusting interatomic interactions.

Abstract

Scaling magnets down to where quantum size effects become prominent triggers quantum tunneling of magnetization (QTM), profoundly influencing magnetization dynamics. Measuring magnetization switching in an Fe atomic chain under a carefully tuned transverse magnetic field, we observe a non-monotonic variation of magnetization lifetimes around a level crossing, known as the diabolic point (DP). Near DPs, local environment effects causing QTM are efficiently suppressed, enhancing lifetimes by three orders of magnitude. Adjusting interatomic interactions further facilitates multiple DPs. Our study provides a deeper understanding of quantum dynamics near DPs and enhances our ability to engineer a quantum magnet.