Conductance Oscillations in the Hybridization Gap of InAs/GaSb Quantum Spin Hall Insulators

Motivated by recent theoretic works [1, 2] we study the electrical transport properties of InAs/GaSb quantum spin Hall (QSH) insulator under perpendicular magnetic fields up to 35 T. In this talk, we report anomalous conductance oscillations in the hybridization gap for both InAs/GaSb and InAs/GaInSb systems. The bulk oscillations, which are approximately periodic in 1/B, originate from the Landau spectrum in inverted band structure, and the observed period is closely related to the degree of band inversion. Simultaneously, we observe a strong conductance peak emerging at field B > 11 T. The strong peak does not follow the above-mentioned 1/B pattern and is accompanied by increasing noise at its onset. We interpret that the strong peak represents a metallic phase arising from gap-closing during the topological transition between the QSH phase and the integer quantum Hall phase. In tilted magnetic fields, the conductance peak shows distinctly different behaviors, depending on shallow inverted or deeply inverted regime.

References:
[1] L. Zhang, X.-Y. Song, and F. Wang, Phys. Rev. Lett. 116, 046404 (2016).
[2] J. Knolle and N. R. Cooper, Phys. Rev. Lett. 118, 176801 (2017).