Epitaxial Gd(00•1) was investigated with spin-polarized low-energy-electron diffraction and the magneto-optic Kerr effect. The ferromagnetic critical temperature of the surface layer was found to lie up to 22K above the bulk Curie point, demonstrating the existence of surface-enhanced magnetic order. Furthermore, spin-resolved photoemission spectroscopy reveals that the 4f spins of the surface were not ferromagnetically coupled to the bulk moments.

Observation of Surface-Enhanced Magnetic Order and Magnetic Surface Reconstruction on Gd(0001). D.Weller, S.F.Alvarado, W.Gudat, K.Schröder, M.Campagna: Physical Review Letters, 1985, 54, 1555-8