Aharonov-Bohm oscillations in (Bi_1-xSb_x)₂Se₃ topological insulator nanoribbon

The 0- and π-phase Aharonov-Bohm (AB) oscillations have been theoretically predicted in one-dimensional (1D) topological insulators (TIs). Here, we report the experimental observations of highly coherent AB oscillations in (Bi_1-xSb_x)₂Se₃ TI nanoribbon with varying temperature, gate voltage and channel length. Temperature dependence of the AB oscillations can be understood by a thermal broadening effect of 1D subbands of the topological surface state. When the channel length increases, the observed AB oscillations resemble a disorder-induced dephasing effect of the DOS. Our experimental results provide a direct evidence that the topologically-protected surface states are quantized along the TI nanoribbon circumference and form 1D subbands to exhibit a unique quantum electronic transport properties.