Effects of short-range magnetic order on photoemission and inverse photoemission spectra in iron

The dependenc of spin-resolved photoemission and inverse photoemission spectra on short-range magnetic order below and aboveT c is investigated within a bulk interband transition model. The spectra are calculated in a 2000-atom cluster of bcc-Fe with local exchange field configurations, which are random subject to an assumed spin-correlation function. The model continuously bridges the gap between the “disordered-local-moment picture” (no short-range order) and a “local-band picture” (massive short-range order). Special emphasis is given to the analysis of factors like group velocity and the symmetry of the wave function by investigating special points in the Brillouin zone. Comparison with experimental data reveals a short-range order of at least 4 A (corresponding to a nearest-neighbour correlation of about 0.4) nearT c .