A magnetic origin was proposed for the honeycomb reconstruction of metallic surfaces with threefold symmetry, such as Pb/Ge (111). Assuming that the ground state was an antiferromagnet insulator over the triangular lattice of adatom sites (Pb), it was demonstrated that the former was simultaneously unstable to canting and to a structural distortion if the surface was soft enough. A net magnetization over the reconstructed surface was therefore predicted at sufficiently low temperatures.

Metallic Surface Reconstruction Driven by Frustrated Antiferromagnetism. J.P.Rodriguez, E.Artacho: Physical Review B, 1999, 59, R705-8