Magnetoelectric coupling and surface anomalous Hall effect

Abstract

Trabajo presentado al: "Spin-orbit-driven transverse transport phenomena" celebrado en Rhöndorf (Alemania) del 3 al 6 de Diciembre de 2012.In this presentation I will review some recent developments in the theory of the linear magnetoelectric (ME) effect in solids. Special emphasis will be put on the orbital-magnetization response to an applied electric field. Remarkably, this contribution contains a term which is purely geometric, in that it can be expressed solely in terms of the Berry potential of the Bloch states in k-space. Like the Berry-phase electronic polarization in crystals, this term is only well-defined modulo a quantum of indeterminacy. While the bulk polarization produces a bound surface charge, the geometric ME response gives rise to a surface anomalous Hall conductance, which in strong topological insulators amounts to half a quantum of conductance. In conventional magnetoelectrics the geometric term is not quantized, and gives only part of the orbital ME response. Ab initio calculations of the linear ME coefficient will be presented for both topological (Bi2Se3) and conventional (Cr2O3) insulators.Peer Reviewe