Nonlocal electron correlations in an itinerant ferromagnet

we show that in itinerant ferromagnets like cobalt the electron correlations are of nonlocal origin, manifested in a complex self-energy Σσ(E,k) that disperses as function of spin σ, energy E, and momentum vector k.
Ch. Tusche et al., Nature Communications, Vol. 9 - 1, pp. 3727 (2018)