Conductance Fluctuations in Disordered 2D Topological Insulator Wires: From Quantum Spin-Hall to Ordinary Phases

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Hsiu-Chuan Hsu¹, Ioannis Kleftogiannis¹, Guang-Yu Guo¹^,², and Víctor A. Gopar³

+ Affiliations

¹Department of Physics, National Taiwan University, Taipei 10617, Taiwan²Physics Division, National Center for Theoretical Sciences, Hsinchu 30013, Taiwan³Departamento de Física Teórica and BIFI, Universidad de Zaragoza, Pedro Cerbuna 12, E-50009, Zaragoza, Spain

Received July 19, 2017; Accepted December 25, 2017; Published February 1, 2018

Impurities and defects are ubiquitous in topological insulators (TIs) and thus understanding the effects of disorder on electronic transport is important. We calculate the distribution of the random conductance fluctuations P(G) of disordered 2D TI wires modeled by the Bernevig–Hughes–Zhang (BHZ) Hamiltonian with realistic parameters. As we show, the disorder drives the TIs into different regimes: metal (M), quantum spin-Hall insulator (QSHI), and ordinary insulator (OI). By varying the disorder strength and Fermi energy, we calculate analytically and numerically P(G) across the entire phase diagram. The conductance fluctuations follow the statistics of the unitary universality class β = 2. At strong disorder and high energy, however, the size of the fluctuations δG reaches the universal value of the orthogonal symmetry class (β = 1). At the QSHI-M and QSHI-OI crossovers, the interplay between edge and bulk states plays a key role in the statistical properties of the conductance.

https://doi.org/10.7566/JPSJ.87.034701

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Conductance Fluctuations in Disordered 2D Topological Insulator Wires: From Quantum Spin-Hall to Ordinary Phases

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