Inelastic neutron scattering and frequency domain magnetic resonance studies of S=4 and S=12 Mn$_6$ single-molecule magnets

TL;DR

This study uses inelastic neutron scattering and magnetic resonance to analyze how small structural changes affect the magnetic energy levels and reversal barriers in Mn6 single-molecule magnets, revealing limitations of the giant spin model.

Contribution

It demonstrates that structural distortions significantly impact the magnetic properties and energy levels, and shows the importance of excited multiplets in low-spin Mn6 molecules.

Findings

Structural distortions alter energy level diagrams.

Giant spin model fails for these molecules.

Excited multiplets influence magnetization barriers.

Abstract

We investigate the magnetic properties of three Mn$_6$ single molecule magnets by means of inelastic neutron scattering and frequency domain magnetic resonance spectroscopy. The experimental data reveal that small structural distortions of the molecular geometry produce a significant effect on the energy level diagram and therefore on the magnetic properties of the molecule. We show that the giant spin model completely fails to describe the spin level structure of the ground spin multiplets. We analyze theoretically the spin Hamiltonian for the low spin Mn$_6$ molecule (S=4) and we show that the excited $S$ multiplets play a key role in determining the effective energy barrier for the magnetization reversal, in analogy to what was previously found for the two high spin Mn6 (S=12) molecules [S. Carretta et al., Phys. Rev. Lett. 100, 157203 (2008)].