Condensed Matter Seminar: Time reversal invariant impurity effects on failure of quantized quantum spin Hall conductance

Xin Chen (Tsinghua University)
Quantum spin Hall effect in time-reversal-invariant (TRI) topological insulators has been proposed for years.

November 11, 2020

Xin Chen (Tsinghua University)
Online Seminar
Mon 16. November 2020, 11:30 am (MEZ)

Abstract:

Quantum spin Hall effect in time-reversal-invariant (TRI) topological insulators has been proposed for years. However, the spin Hall conductance measured experimentally is not precisely quantized as suggested by theory. In this talk, we consider a quantum spin Hall model with an TRI impurity placed nearby the edge. We show the existence of two bound states in the band gaps resonant with the edge modes. The bound states form Kondo impurity spontaneously and break the time reversal invariance. We further show hopping between edge modes and bound states generate back scattering when considering interaction between edge modes. Finally, we show the hopping is enhanced due to Kondo effect.

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