Band Calculation for Ce-Compounds on the basis of Dynamical Mean Field Theory(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

概要

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The band calculation scheme for ƒ electron compounds is developed on the basis of the dynamical mean field theory (DMFT) and the LMTO method. The auxiliary impurity problem is solved by a method named as NCAƒ^2v', which includes the correct exchange process of the ƒ^1→ƒ^2 virtual excitation as the vertex correction to the non-crossing approximation (NCA) for the ƒ^1→ƒ^0 fluctuation. This method leads to the correct magnitude of the Kondo temperature, T_K, and makes it possible to carry out quantitative DMFT calculation including the crystalline field (CF) and the spin-orbit (SO) splitting of the self-energy. The magnetic excitation spectra are also calculated to estimate T_K. It is applied to Ce metal and CeSb at T=300K as the first step. In Ce metal, the hybridization intensity (HI) just below the Fermi energy is reduced in the DMFT band. The photo-emission spectra (PES) have a conspicuous SO side peak, similar to that of experiments. T_K is estimated to be about 70K in γ-Ce, while to be about 1700K in α-Ce. In CeSb, the double-peak-like structure of PES is reproduced. The HI is enhanced just at the Fermi energy in the DMFT band of CeSb. Therefore, T_K〜60K, which is comparable to but slightly larger than the experimental value, is obtained.
社団法人日本物理学会の論文
2005-09-15