Longer Living Majority than Minority Image State at Fe(110)

A strongly spin-dependent lifetime is reported for the $n=1\mathrm{}$ image-potential surface state at Fe(110). Spin-resolved inverse photoemission measurements reveal an intrinsic linewidth of $140\pm 10$ meV for the minority image state, about twice as large as the $70\pm 10$ meV observed for the majority state. The spin dependence of the lifetime can be explained in terms of the spin-dependent density of bulk electronic states in iron, on the assumption that escape into bulk states accompanied by electron-hole-pair production is the main decay channel. The binding energies are magnetically split by $57\pm 5$ meV. This result supports the predicted predominant influence of the spin-polarized substrate potential on the binding energy, modified by a small effect of the spin-polarized surface barrier.