ELECTRONIC AND MAGNETIC-STRUCTURE OF A CR MONOLAYER ON AG(100)

Angle-resolved photoemission is used to study the electronic structure of the Cr layers obtained by condensing one layer equivalent (LE), or less, of Cr on Ag(100) at low (approximately 0.5 LE/min) deposition rates. The data confirm our earlier finding that, upon deposition on a mildly (approximately 440 K) heated substrate, layer-by-layer growth takes place up to 1 LE, i.e., an ordered flat Cr monolayer with a good degree of perfection is formed. The substrate temperature during deposition is critical since lower (approximately 300 K) or higher (approximately 500 K) temperatures result in an inhomogeneous rough Cr layer. For the ordered flat monolayer the characteristic two-dimensional dispersion of the Cr 3d energy bands and their symmetry at GAMMA-BAR is determined. It is argued that when considered together with electron-diffraction observations, which reveal a weak c(2 X 2) pattern at low energies (less-than-or-equal-to 30 eV), the photoemission results provide compelling evidence of a monolayer stabilized by antiferromagnetic order. The large energy gap at the Fermi energy indicates that the effect must be very strong with a local moment in the range (3-4)mu-B, as predicted theoretically.