Substitutional adsorption mechanism and controllable magnetic properties of Mn on PbTe(1 1 1) surface

Abstract

Adsorption of Mn adatom on PbTe(1 1 1) surface is investigated by first-principle calculations. A subsurface substitutional adsorption mechanism is found. MnTe bond is stronger and shorter than PbTe bond. This leads to competition. Because of stronger MnTe bond, Mn atoms prefer to be deep into bulk crystal in order to maximum the number of MnTe bond. But the MnTe bonds cannot relax to gain their maximum strength because of the rigidity of the bulk crystal. At the outmost surface layer Mn atoms can relax maximum but the number of MnTe bond is only half of that in bulk. The 2nd layer is the best choice and Mn atoms prefer to form a (3×3)R 30°pattern, in well agreement with recent experimental work. More importantly, its magnetic state is strain-dependent and this opens a new avenue to fabricate spintronics and spin caloritronics with a high tunneling magnetothermopower based on PbTe. © 2012 Elsevier B.V. All rights reserved.