2–27 May 2016
Nordita, Stockholm
Europe/Stockholm timezone

Self-organized semi-metals on grain boundaries in topological band insulators

26 May 2016, 10:00
1h
122:026 (Nordita, Stockholm)

122:026

Nordita, Stockholm

Speaker

Robert-Jan Slager

Description

Semi-metals are characterized by nodal band structures that give rise to exotic electronic properties. The stability of Dirac semi-metals, such as graphene in two spatial dimensions (2D), requires the presence of lattice symmetries, while akin to the surface states of topological band insulators, Weyl semi-metals in three spatial dimensions (3D) are protected by band topology. I will show that in the bulk of topological band insulators, self-organized topologically protected semi- metals can emerge along a grain boundary, a ubiquitous extended lattice defect in any crystalline material. In addition to experimentally accessible electronic transport measurements, these states exhibit a valley anomaly that influences the edge spin transport in two spatial dimensions (2D), whereas in 3D they appear as graphene-like states that should exhibit an odd-integer quantum Hall effect. The general mechanism underlying these novel semi-metals, being the hybridization of spinon modes bound to the grain boundary, suggests  that topological semi-metals can emerge in any topological material where lattice dislocations bind localized topological modes.

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