Quantum tunneling in a three dimensional network of exchange coupled single-molecule magnets

TL;DR

This study demonstrates that quantum tunneling of magnetization in Mn4 single-molecule magnets persists despite three-dimensional exchange coupling, enabling precise measurement of weak intermolecular interactions.

Contribution

It reveals that exchange coupling causes an exchange bias in quantum resonances, allowing detailed analysis of weak intermolecular hydrogen bonds in SMMs.

Findings

Quantum tunneling is not suppressed by exchange coupling.

Exchange bias enables precise measurement of intermolecular interactions.

Minor hysteresis loops reveal detailed resonance structures.

Abstract

A Mn4 single-molecule magnet (SMM) is used to show that quantum tunneling of magnetization (QTM) is not suppressed by moderate three dimensional exchange coupling between molecules. Instead, it leads to an exchange bias of the quantum resonances which allows precise measurements of the effective exchange coupling that is mainly due to weak intermolecular hydrogen bounds. The magnetization versus applied field was recorded on single crystals of [Mn4]2 using an array of micro-SQUIDs. The step fine structure was studied via minor hysteresis loops.