Low-energy spin excitations in the molecular magnetic cluster V ₁₅

Abstract

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