Two-body tunnel transitions in a Mn4 Single-Molecule Magnet

TL;DR

This paper enhances the understanding of quantum tunneling in single-molecule magnets by incorporating two-body transitions like spin-spin cross-relaxation, revealing new resonances in Mn4 SMMs.

Contribution

It introduces a model including two-body tunnel transitions mediated by dipolar and superexchange interactions, improving the explanation of experimental data.

Findings

Identification of additional quantum resonances due to SSCRs

Observation of steps in hysteresis loops at specific fields

Demonstration of two-body transitions' significance in SMMs

Abstract

The one-body tunnel picture of single-molecule magnets (SMMs) is not always sufficient to explain the measured tunnel transitions. An improvement to the picture is proposed by including also two-body tunnel transitions such as spin-spin cross-relaxation (SSCR) which are mediated by dipolar and weak superexchange interactions between molecules. A Mn4 SMM is used as a model system. At certain external fields, SSCRs lead to additional quantum resonances which show up in hysteresis loop measurements as well defined steps.