Spin-Hamiltonian theory of orbital near-degenerate state in tetragonal field

Abstract In this paper, a Spin-Hamiltonian theory of orbital near-degenerate state in tetragonal field is presented. For orbital doublet 2 E, which is an orbital degenerate state in the cubic field and is a near-degenerate state in the tetragonal field, we obtain the cubic invariant form and the tetragonal invariant form of the Spin-Hamiltonian. In case of near-degeneracy (tetragonal splitting is very small) two additional g -factors are introduced to investigate Zeeman-splitting for tetragonal field. The two additional g -factors g 2 z and g 2 xy describe the magnetic interest between A 1 g and B 1 g states for a parallel magnetic field with z -axis and a perpendicular magnetic field with z -axis, respectively. The theory is based on the time-reversal invariant and the point-group symmetry invariant. The theoretical method can also be used for other orbital degenerate states 2 S +1 Γ including S > 1 2 and Γ =T 1 or T 2 and can be used for other point-group symmetry.