Phys. Rev. Lett. 77 (1996) pp. 908-911

Unexpected Negative Exchange Splitting of the Fe(001) Image State

S. De Rossi and F. Ciccacci

Istituto Nazionale di Fisica della Materia-Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano, Italy

S. Crampin

School of Physics, University of Bath, BA2 7AY, United Kingdom

Abstract
We have observed a surprising negative exchange splitting of the n = 1 image-potential surface state at Fe(001) using spin resolved inverse photoemission, indicating that the minority-spin level has a lower energy than the majority-spin level. Calculations show the negative sign results from two superimposing effects. A true reverse polarization of the image state, which hybridizes with bulk bands, which is then enhanced by matrix element effects in inverse photoemission.