George Sawatzky
Physics Department, University of British Columbia, Canada
Date
30 November 2011
Host
Manfred Sigrist
Title
Magnetism Based on Surfaces, Interfaces and Point Defects
Abstract
Controlled surfaces, interfaces and heterostructures as well as point defects provide a new possible source of (nano) magnetic materials not dependent on the presence of conventional magnetic elements. I will present some ideas and calculations which point towards magnetic materials with high transition temperatures involving polar surfaces, cation vacancies in Oxides or anion substitution in nonmagnetic oxides. Recalling that molecular Oxygen is in a triplet state and that Hunds’ rule coupling of 2p electrons in Oxygen is as large as that in 3d transition metal compounds provides hope for new classes of magnetic materials. Recent reports of magnetic order in oxide heterostructures, cation vacancy rich MgO, proton implanted graphite, alkali superoxides, and N substituted MgO, are just a few examples of discoveries based on theoretical and conceptual ideas. I will present some of these often rather simple basic physics based ideas and some density functional based calculations to support these claims.