Theory of photoelectron spectra from inner-core states. II. Temperature effect and role ofd-electron correlations

Finite-temperature effects and the role of d-electron correlations on the inner-core photoelectron spectra of transition metals are numerically investigated on the basis of a theory developed by Kakehashi, Becker, and Fulde. It is verified that the total cross section ($I_{+}$+$I_{\mathrm{-}}$) hardly changes below and above the Curie temperature in typical transition metals. It is predicted that the multiplet peaks for each spin component strongly depend on the temperature in the ferromagnetic state. This property provides us with a method for determining experimentally the origin of splittings in ferromagnetic metals by means of a spin-polarization analysis. It is shown that the existence of the Coulomb interaction U between d electrons enhances the atomic characteristics of the spectra. In particular the line shape is strongly modified in the intermediate region where U is comparable to the d-band width. Thus the inclusion of U is decisively important for an understanding of the inner-core spectra of transition metals.