Interplay between Electronic Structure and Correlation through the s-d Mixing in Transition Metal Systems

The s-d mixing which refers to the mixing between d states of a transition element atom and states of s, p, f,… symmetries of neighboring atoms can be of primary importance even in transition metal systems. A mechanism for enhancing the ferromagnetism of iron atom systems through the s-d mixing with s, p valence atoms such as B, C and N which seems to be operating in Nd2Fe14B and other systems is discussed as an illustrative example of the static perturbation effect. A possible role of the s-d mixing in producing the discrepancies of the band structure calculation from the experimental data on single electron excitations in nickel is discussed by extending the discussion on impurities.