Evolutions of helical edge states in disordered HgTe/CdTe quantum wells

Abstract

We study the evolutions of the nonmagnetic disorder-induced edge states with the disorder strength in the HgTe/CdTe quantum wells. From the supercell band structures and wave-functions, it is clearly shown that the conducting helical edge states, which are responsible for the reported quantized conductance plateau, appear above a critical disorder strength after a gap-closing phase transition. These edge states are then found to decline with the increase of disorder strength in a stepwise pattern due to the finite-width effect, where the opposite edges couple with each other through the localized states in the bulk. This is in sharp contrast with the localization of the edge states themselves if magnetic disorders are doped which breaks the time-reversal symmetry. The size-independent boundary of the topological phase is obtained by scaling analysis, and an Anderson transition to an Anderson insulator at even stronger disorder is identified, in-between of which, a metallic phase is found to separate the two topologically distinct phases.

7 pages, 5 figures

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• Modification and Control of Topological Insulator Surface States Using Surface Disorder
• Interplay of interactions, disorder and topology in the Haldane-Hubbard model
• Robust topological insulator surface conduction under strong surface disorder
• Percolating States in the Topological Anderson Insulator
• Disorder-induced phase transition in Dirac systems beyond the linear approximation
• Weak quantization of non-interacting topological Anderson insulator
• Effects of disorder on electron tunneling through helical edge states
• Disorder-induced topological phase transition in HgCdTe crystals
• Probing the Topological Anderson Transition in Quasiperiodic Photonic Lattices via Chiral Displacement and Wavelength Tuning
• Bulk effects on topological conduction on the surface of 3-D topological insulators
• Disorder-induced phase transitions in double HgTe quantum wells
• Acoustic topological Anderson insulators
• Anomalous Non-Hermitian Topological Anderson Insulator