Topological antiferromagnetism at Cr surfaces and interfaces

Abstract

The Hubbard tight-binding Hamiltonian is used to derive the local magnetic moments of vicinal Cr surfaces and interfaces. For Cr vicinal surfaces, the magnetic arrangement is a double-cell configuration which consists of monoatomic steps antiferromagnetically coupled to nearest-neighbor monoatomic steps. These results allow us to explain the apparently contradictory observations obtained by spin-resolved and angle-and-energy-resolved photoemission. For the Fe monolayer on vicinal Cr surfaces, a magnetic configuration with a periodicity of two steps is also obtained. As a consequence, the sign of the magnetization at the Fe overlayer oscillates from step to step. This result is in agreement with recent experiments using scanning-electron-microscopy with polarization analysis and magneto-optic Kerr effect.