Metallic Surface Reconstruction Driven by Frustrated Antiferromagnetism

A magnetic origin for the honeycomb reconstruction of metallic surfaces with three-fold symmetry like Pb/Ge (111) is proposed. Assuming that the groundstate is an antiferromagnet insulator over the triangular lattice of adatom sites (Pb), we demonstrate that the former is simultaneously unstable to canting and to a structural distortion if the surface is soft enough. We therefore predict a net magnetization over the reconstructed surface at sufficiently low temperature. PACS Indices: 75.30.Pd, 73.20.At, 79.60.Dp ∗ Permanent address: Dept. of Physics and Astronomy, California State University, Los Angeles, CA 90032, USA.