Electron-nuclear quadrupole interaction in exchange clusters

Abstract

The interaction of the electronic shell of a tetrahedral antiferromagnetic cluster with quadrupole nuclear moments is investigated. The orbital degeneracy of the ground state of the exchange cluster is responsible for hybrid states. Transitions between hybrid electron-nuclear states allows the observation of resonance absorption of an electromagnetic field, even in those cases when the local crystal fields possess cubic symmetry and individual ions exist in orbitally non-degenerate states. The dependence of the nuclear quadrupole resonance on the hybrid states is examined. It is shown that static distortions lead to the destruction of the hybrid states. The joint influence of both distortion and magnetic field is considered. The possibility of new essential peculiarities in the N.Q.R. spectrum is predicted.