  We investigated interfaces of halfmetallic Co2MnSi(100) Heusler thin films
with Ag(100), Cr(100), Cu and Al layers relevant for spin valves by high energy
x-ray photoemission spectroscopy (HAXPES). Experiments on Co2MnSi samples with
an Ag(100) interface showed a characteristic spectral shoulder feature close to
the Fermi edge, which is strongly diminished or suppressed at Co2MnSi (100)
interfaces with the other metallic layers. This feature is found to be directly
related to the Co2MnSi(100) layer, as reflected by control experiments with
reference non-magnetic films, i.e. without Heusler layer. By comparison with
HAXPES calculations, the shoulder feature is identified as originating from an
interface state related to a highly spin polarized surface resonance of Co2MnSi
(100).
