Adjustable Quantum Interference Oscillations in Sb-Doped Bi<sub>2</sub>Se<sub>3</sub> Topological Insulator Nanoribbons.

Kim, Hong-Seok; Hwang, Tae-Ha; Kim, Nam-Hee; Hou, Yasen; Yu, Dong; Sim, H-S; Doh, Yong-Joo · ACS Nano · 2020

basic_science · Level V

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Abstract

Topological insulator (TI) nanoribbons (NRs) provide a platform for investigating quantum interference oscillations combined with topological surface states. One-dimensional subbands formed along the perimeter of a TI NR can be modulated by an axial magnetic field, exhibiting Aharonov-Bohm (AB) and Altshuler-Aronov-Spivak (AAS) oscillations of magnetoconductance (MC). Using Sb-doped Bi<sub>2</sub>Se<sub>3</sub> TI NRs, we found that the relative amplitudes of the two quantum oscillations can be tuned by varying the channel length, exhibiting crossover from quasi-ballistic to diffusive transport regimes. The AB and AAS oscillations were discernible even for a 70 μm long channel, while only the AB oscillations were observed for a short channel. Analyses based on ensemble-averaged fast Fourier transform of MC curves revealed exponential temperature dependences of the AB and AAS oscillations, from which the circumferential phase-coherence length and thermal length were obtained. Our observations indicate that the channel length in a TI NR can be a useful control knob for tailored quantum interference oscillations, especially for developing topological hybrid quantum devices.