Low-energy spin excitations in the molecular magnetic cluster V15

TL;DR

This study uses Inelastic Neutron Scattering to investigate low-energy spin excitations in the V15 molecular magnetic cluster, revealing key exchange interactions and energy gaps influenced by geometric frustration and symmetry deviations.

Contribution

First direct measurement of exchange coupling and energy gap in V15 cluster using INS, highlighting effects of symmetry deviations and DM interactions.

Findings

Effective exchange coupling J0 = 0.211 meV

Energy gap 2Δ = 0.035 meV

Influence of symmetry deviations and DM interactions

Abstract

We report an Inelastic Neutron Scattering (INS) study of the fully deuterated molecular compound K6[V15As6O42].9(D2O) (V15). Due to geometrical frustration, the essential physics at low temperatures of the V15 cluster containing 15 coupled V4+ (S=1/2) is determined by three weakly coupled spin-1/2 on a triangle. The INS spectra at low-energy allow us to directly determine the effective exchange coupling J0 = 0.211 meV within the triangle and the gap 2 \Delta = 0.035(2)meV between the two spin-1/2 doublets of the ground state. Results are discussed in terms of deviations from trigonal symmetry and Dzyaloshinskii-Moriya (DM) interactions.