YCo2:: Intrinsic magnetic surface of a paramagnetic bulk material

Here we report on results of a spin-resolved photoelectron spectroscopic (SRPES) study of YCo2 thin films (150 angstrom-thick) grown on a W(110) substrate. The films were prepared by co-deposition of stoichiometric amounts of Y and Co onto a clean W surface followed by thermal annealing leading to (2 x 2) overstructure with respect to W(110) in the low-energy electron diffraction pattern indicated formation of a structurally ordered YCo2(111) surface. While no clear spin asymmetry was observed for bulk-sensitive SRPES data taken at h nu=1253.6 eV, the more surface-sensitive SRPES data obtained at h nu=21.2 eV photon energy revealed a clear spin-asymmetry probing the validity of the recent theoretical prediction.