Modulation of the universal conductance fluctuations by broken time-reversal symmetry in topological insulator

In topological insulator BiSbTeSe2 nanowire device, we extract the conductance fluctuations and study their magnetic field dependence in the gate-dependent transport of topological electrons. With the magnetic field increasing, the conductance fluctuation magnitudes are found to reduce by a ratio of √2 and form a quantized step, and this is observed both in n-type and p-type transport. This is related to the breaking of the time reversal symmetry of three-dimensional topological insulators, which reveal a crossover of the symmetry classes.