“Topological Magneto-Electric effect decay” by Dima Pesin (University of Utah)

Date: 
Wednesday, February 27, 2013 - 4:00pm
Series: 
Condensed Matter Seminars

 

An effective magnetic monopole is induced by an external charge in a 

topological insulator, and in an ordinary insulator covered by a graphene sheet 

or another two-dimensional electron system, when it has a perfect surface 

quantum Hall effect [X.-L. Qi, R. Li, J. Zang, and S.-C. Zhang, Science {323}, 1184 

(2009)]. We discuss the observability of this magnetoelectric response under the 

realistic conditions of a quantum Hall effect that is imperfect because of finite 

temperature, disorder, or unintended doping. By generalizing the surface 

electrodynamics to allow for a finite longitudinal conductivity, we analyze the 

transient behavior which occurs as the potential from a suddenly introduced 

external charge is screened. Screening severely limits the experimental time 

scales on which observation of magnetic-monopole-related phenomena is 

possible. We estimate the longitudinal conductivity values that are necessary for 

the monopole to survive for an extended period of time and discuss implications 

of our findings for other transport properties of the surface.