Spin-polarized angle-resolved photoemission study of the electronic structure of Fe(100) as a function of temperature

Abstract

By spin- and angle-resolved photoemission with synchrotron radiation the electronic structure of Fe(100) has been tested between room temperature and the Curie temperature $T_C$ for photon energies in the range 20–70 eV. The spin-resolved energy-distribution curves (SREDC’s) reflect the dispersions of the ${\Delta }_5^{\uparrow }$,↓-symmetry initial-state bands. This manifests in an abrupt change in spin character of the peak near $E_F$ from predominantly minority spin to majority spin when tuning the photon energy across 33 eV. The non-spin-resolved EDC’s thereby remain nearly unchanged. Upon heating to 0.85T/$T_C$, depending on photon energy, qualitative different changes in the SREDC’s are observed: At hν=60 eV, ${\Gamma }_{25}^{\mathcal{’}\uparrow }$ is found to be stationary in energy upon heating, and the spin-summed intensity decreases by less than 5%. At ${\Gamma }_{25}^{\mathcal{’}\downarrow }$, a strong loss of intensity occurs. In contrast, at hν=31 and 21 eV, an increase in minority-spin (and total) photocurrent upon heating is observed. This is interpreted as resulting from a decrease of the exchange splitting with temperature near H.