The properties of exchange-coupled triads of Cr3+ions in ruby

Abstract
The eigenstates and eigenvalues for a triad consisting of three exchange-coupled Cr3+ ions in ruby are derived from a phenomenological spin Hamiltonian. The terms included in the Hamiltonian are the isotropic, anisotropic and antisymmetric exchange interactions together with the single ion zero field term and dipole-dipole interaction term. The importance of each term is discussed in relation to various possible triads in ruby.