TOPOLOGICAL ANTIFERROMAGNETISM AT CR SURFACES AND INTERFACES

The Hubbard tight-binding Hamiltonian is used to derive the local magn etic moments of vicinal Cr surfaces and interfaces. For Cr vicinal sur faces, the magnetic arrangement is a double-cell configuration which c onsists of monoatomic steps antiferromagnetically coupled to nearest-n eighbor monoatomic steps. These results allow us to explain the appare ntly contradictory observations obtained by spin-resolved and angle-an d-energy-resolved photoemission. For the Fe monolayer on vicinal Cr su rfaces, a magnetic configuration with a periodicity of two steps is al so obtained. As a consequence, the sip of the magnetization at the Fe overlayer oscillates from step to step. This result is in agreement wi th recent experiments using scanning-electron-microscopy with polariza tion analysis and magneto-optic Kerr effect.