The story of Dirac masses and their topological defects in graphene - like systems

Datum

18.12.2012

Zeit

16:40 - 18:10

Sprecher

Prof. Dr. Igor Herbut

Zugehörigkeit

Simon Fraser University/MPI - PKS

Serie

TUD Physikalisches Kolloquium

Sprache

en

Hauptthema

Physik

Andere Themen

Physik

Beschreibung

I will discuss the spectrum of quasiparticles in the Dirac systems like graphene, in the presence of domain walls, vo rtices, or hedgehogs of superconducting and/or insulating order parameters. These orders formally appear as the mass terms in the Dirac equation, and their topological defects have been known to carry non - trivial quantum numbers such as charge and spin. In the talk I will discuss their additional internal degree of freedom: irrespectively of the nature of orders that support the defect, an extra mass order parameter is found to spontaneously emerge in their core. The particle - hole symmetry restricts the def ects to carry the quantum numbers of a single effective isospin 1/2, quite independently of the values of their electric charge or true spin. Some examples of this new degree of freedom in graphene and on surfaces of topological insulators will be given, a nd connections to the mathematics of Clifford algebras will be briefly mentioned.

Letztmalig verändert: 18.12.2012, 09:04:31