"Effects of disorder and dimerization on the surface states of weak 3D topological insulators" Hideaki Obuse

Effects of disorder and dimerization on the surface states of weak 3D topological insulators

Prof. Hideaki Obuse 
Hokkaido University, Japan

• Date: Wednesday, 29 October
• Time: 14:00-15:00
• Venue: Meeting Room C015, Lab1

Abstract:
The topological insulators(TI) are classified into strong and weak TIs. The weak three-dimensional (3D) topological insulator is realized by stacking the strong two-dimensional(2D) topological insulators, that is, quantum spin Hall insulators. Recently, it has been identified experimentally that Bi14Rh3I9 is such a material. In this work, we study effects of disorder and dimerization of interlayer couplings on the 2D surface states of weak 3D topological insulators by constructing an effective model, called, spin-directed Z_2 network model. It is found that, without dimerization, the network model has no insulating phase for any disorder strength. However, a sufficiently strong dimerization induces a transition from a metallic phase to an insulating phase. The critical exponent for the diverging localization length at metal-insulator transition points is obtained by finite-size scaling analysis of numerical data from simulations of this network model. It is shown that the phase transition belongs to the two-dimensional symplectic universality class of the Anderson transition.

Reference: H. Obuse, S. Ryu, A. Furusaki, and C. Mudry, PRB 89, 155315 (2014)

Looking forward to seeing many of you.

Quantum Systems Unit