Collect. Czech. Chem. Commun. 2004, 69, 34-46

Magnetic Linear Birefringence in Rare Earth Systems. II. Third-Order Approach

Lidia Smenteka,b

a Institute of Physics, N. Copernicus University, Toruń, Poland
b Department of Chemistry, Vanderbilt University, Nashville, U.S.A.


The theory of linear magnetic birefringence of rare earth ions in crystals is extended here by the contributions that represent a direct perturbing influence of the crystal field potential surrounding the central ion. The basic assumptions of the theoretical model are the same as in the previous analysis of second-order terms. The third-order contributions introduced here break the free ionic system approximation, and they represent the impact due to configuration interaction. The effective operators include the perturbing influence of the excitations from the 4f shell to one-electron states of the same parity (as previously at the second order), and in addition, the excitations to states of opposite parity. All contributing terms are expressed by the effective operators that are defined within the perturbed function approach. The tensorial structure of these operators is discussed, and special attention is directed to newly defined radial integrals. The values of all radial integrals that are necessary for the third-order numerical analysis are presented in the case of all lanthanide ions.

Keywords: Rare earth ions; Lanthanides; Magnetic anisotropy; Polarizability tensor; Effective tensor operators; Perturbation theory; Crystal field potential; Perturbed function approach.

References: 9 live references.