Gate-Tunable Transport in Quasi-One-Dimensional α-Bi4I4 Field Effect Transistors
- The Ohio State Univ., Columbus, OH (United States)
- Univ. of Texas at Dallas, Richardson, TX (United States)
- Univ. of Texas at Dallas, Richardson, TX (United States); Seoul National Univ. (Korea, Republic of)
- National Institute for Materials Science (NIMS), Tsukuba (Japan)
- Rice Univ., Houston, TX (United States)
- Univ. of California, Berkeley, CA (United States)
Bi4I4 belongs to a novel family of quasi-one-dimensional (1D) topological insulators (TIs). While its β phase was demonstrated to be a prototypical weak TI, the α phase, long thought to be a trivial insulator, was recently predicted to be a rare higher order TI. Here, we report the first gate tunable transport together with evidence for unconventional band topology in exfoliated α-Bi4I4 field effect transistors. We observe a Dirac-like longitudinal resistance peak and a sign change in the Hall resistance; their temperature dependences suggest competing transport mechanisms: a hole-doped insulating bulk and one or more gate-tunable ambipolar boundary channels. Our combined transport, photoemission, and theoretical results indicate that the gate-tunable channels likely arise from novel gapped side surface states, two-dimensional (2D) TI in the bottommost layer, and/or helical hinge states of the upper layers. Markedly, a gate-tunable supercurrent is observed in an α-Bi4I4 Josephson junction, underscoring the potential of these boundary channels to mediate topological superconductivity.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES), Materials Sciences & Engineering Division; National Science Foundation (NSF); US Army Research Office (ARO); US Air Force Office of Scientific Research (AFOSR); Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan; Core Research for Evolutional Science and Technology (CREST); Japan Science and Technology Agency (JST)
- Grant/Contract Number:
- AC02-05CH11231; DMR-1922076; DMR-1921581; DMR-1945351; W911NF-18-1-0416; DMR-1921847; NSF-1921798; FA9550-19-1-0037; JP20H00354; JPMJCR15F3
- OSTI ID:
- 1877042
- Journal Information:
- Nano Letters, Vol. 22, Issue 3; ISSN 1530-6984
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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