The calculation of rare-earth levels in layered cobaltates Rx/3CoO2 (x≦1)

We studied theoretically the crystal field and Zeeman split electronic levels of trivalent rare earths that are distributed over trigonal prismatic sites of the layered Rx/3CoO2 system (closely related to sodium cobaltate NaxCoO2). The calculations were done in the whole basis of 4fn configurations (up to 3000 many-electron determinantal functions) for the ideal trigonal symmetry D3h, as well as for the reduced symmetry C2v that takes into account a more distant neighborhood of the R-sites. Detailed data on the doublet and singlet states for Pr, Nd, Sm, Tb and Dy are presented. The obtained g-factor and the van Vleck susceptibility tensor components are used for calculations of anisotropic magnetic susceptibilities and their temperature dependencies.