A note on spin hamiltonians

Abstract

Several papers have reported the observation of transitions induced by acoustic resonance between s_z= +or- 1 of an s=1 ion (with s_z=0 well removed). The standard spin hamiltonian formalism is expected to account for the observations, but difficulties have been encountered in its perturbation treatment. A technique which circumvents these is described. It leads naturally to a description of s_z= +or- 1 as a doublet with fictitious spin=¹/₂. The new spin hamiltonian has an unusual form, and the wider issue of the symmetry property of spin hamiltonians is raised.