Direct observation of mixing of spin-multiplets in an antiferromagnetic molecular nanomagnet by electron paramagnetic resonance

TL;DR

This study uses high-frequency EPR to directly observe spin-multiplet mixing in an antiferromagnetic molecular nanomagnet, revealing S-mixing caused by comparable exchange and anisotropy energies, and demonstrating EPR's potential for studying exchange splittings.

Contribution

First direct EPR evidence of spin-multiplet mixing in a molecular nanomagnet, showing EPR's capability to probe exchange splittings typically studied by neutron scattering.

Findings

EPR detects breaking of ΔS=0 selection rule.

Evidence of S-mixing induced by exchange and anisotropy.

EPR offers enhanced sensitivity for exchange splitting studies.

Abstract

High-frequency electron paramagnetic resonance (EPR) studies of the antiferromagnetic Mn-$[3\times 3]$ molecular grid clearly reveal a breaking of the $\Delta S = 0$ selection rule, providing direct evidence for the mixing of spin wavefunctions ($S$-mixing) induced by the comparable exchange and magneto-anisotropy energy scales within the grid. This finding highlights the potential utility of EPR for studies of exchange splittings in molecular nanomagnets, which is normally considered the sole domain of inelastic neutron scattering, thereby offering improved sensitivity and energy resolution.