Two-body tunnel transitions in a Mn4 single-molecule magnet

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 Mn 4 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.