Mechanism of Ground State Selection in the Frustrated Molecular Spin Cluster V15

TL;DR

This study uses inelastic neutron scattering to investigate the low-energy quantum spin states of the frustrated V15 molecular spin cluster, revealing how symmetry lowering influences ground state selection.

Contribution

It provides a detailed understanding of the ground state mechanism in V15 by mapping INS data onto a distorted S=1/2 Heisenberg triangle model.

Findings

Energy gap between lowest doublets is approximately 27 μeV.

Symmetry lowering causes wavefunction mixing in the ground state.

INS transitions depend on applied magnetic field.

Abstract

We report an inelastic neutron scattering (INS) study under a magnetic field on the frustrated molecular spin cluster $V_{15}$. Several field-dependent transitions are observed and provide a comprehensive understanding of the low-energy quantum spin states. The energy gap $2 \Delta_{0}\approx 27(3)\mu$eV between the two lowest $S=1/2$ Kramers doublets is unambiguously attributed to a symmetry lowering of the cluster. The INS data are mapped onto an S=1/2 Antiferromagnetic Heisenberg triangle with scalene distortion. A quantitative description of the wavefunction mixing within the ground state is derived.