Bose-Operator Expansions of Tensor Operators in the Theory of Magnetism

Using a method of matching corresponding matrix elements, a hermitian Bose-operator expansion of tensor operators of arbitrary rank which transforms all kinematic effects into dynamical interactions between Bose particles is derived. It is shown that the method is a generalization of the Holstein- Primakoff transformation of the angular momentum components.

Tables are given for the Racah operators of rank k up to k=8 in terms of angular momentum operators and in terms of Bose operators. A similar table is given for the Stevens operators for even k up to k=6.