Effect of a finite conduction-band width on XMCD spectra at the L2,3 absorption edges of mixed-valence Ce and Yb compounds in high magnetic fields

Effect of a finite conduction-band width is studied in detail on the spectra of X-ray absorption spectroscopy (XAS) and its X-ray magnetic circular dichroism (XMCD) at the L_2,3 absorption edges of mixed valence Ce and Yb compounds in high magnetic fields. Calculations are made with an extended single impurity Anderson model and within the leading term approximation in the 1/N_f expansion method, where N_f is the degeneracy of the 4f states. It is shown that a model with a vanishing conduction-band width is applicable, as an approximation method, to the calculation of XAS and XMCD spectra for realistic systems with a finite conduction-band width, if the values of the 4f level and the hybridization strength are renormalized appropriately. This justifies the previous calculations on general features of high-magnetic-field XAS and XMCD spectra with zero conduction-band width. At the same time, it is also shown that for more realistic calculations of high-magnetic-field XMCD spectra of some specific mixed-valence Ce and Yb compounds, the present theory with a finite conduction-band width is more appropriate.