Diagnosing the magnetic field-tuned symmetry nature of the topological electrons by conductance fluctuations in bulk-insulating BiSbTeSe2 devices

TL;DR

This study investigates how magnetic fields influence conductance fluctuations in bulk-insulating BiSbTeSe2 topological insulators, revealing symmetry breaking effects through quantized steps in fluctuation magnitudes.

Contribution

It provides experimental evidence of magnetic field-induced symmetry breaking in topological electrons via conductance fluctuation analysis in BiSbTeSe2 devices.

Findings

Conductance fluctuations decrease by a factor of sqrt(2) with increasing magnetic field.

Quantized steps in fluctuation magnitudes indicate time reversal symmetry breaking.

Results are consistent in both n-type and p-type transport and confirmed in nonlocal measurements.

Abstract

We extract the quantum conductance fluctuations and study its magnetic field dependence in the gate-dependent transport of the topological electrons in bulk-insulating BiSbTeSe2 devices. While increasing the magnetic field from 0 to 12 Tesla, the fluctuation magnitudes are found reduced by a ratio of sqrt(2) and form a quantized step. The step is observed both in n-type and p-type transport. It is also confirmed in the nonlocal measurements. This essentially demonstrates the breaking of the time reversal symmetry of the three-dimensional Z2 topological insulators.