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Topological Materials for Low-energy Electronics
Add to Calendar 2021-11-29T20:30:00 2021-11-29T21:30:00 UTC Topological Materials for Low-energy Electronics Password: 342891
Start DateMon, Nov 29, 2021
3:30 PM
End DateMon, Nov 29, 2021
4:30 PM
Presented By
Michael S. Fuhrer, Monash University, Sydney Australia
Event Series: CAMP Seminar

The impending end of Moore’s Law has prompted a search for a new computing technology with vastly lower energy consumed per operation than silicon CMOS. The recent discovery of topological phases of matter offers a possible solution: a “topological transistor” in which an electric field tunes a material from a conventional insulator “off” state to a topological insulator “on” state, in which topologically protected edge modes carry dissipationless current. Due to the combined effects of Rashba spin-orbit interaction and electric field control of the bandgap, the topological transistor may switch at lower voltage, overcoming “Boltzmann’s tyranny”[1]. 

I will discuss our work on atomically thin films of Na3Bi as a platform for a topological transistor. We study thin films of Na3Bi grown in ultra-high vacuum by molecular beam epitaxy[2], characterized with electronic transport, scanning tunneling microscopy (STM), and angle-resolved photoemission spectroscopy (for a review, see Ref. [2]). When thinned to a few atomic layers Na3Bi is a large gap (>300 meV) 2D topological insulator with topologically protected edge modes observable in STM. Electric field applied perpendicular to the Na3Bi film closes the bandgap completely and reopens it as a conventional insulator[3]. Electrical transport measurements demonstrate that the current is carried by helical topological edge modes over millimeter-scale distances[4]. The large bandgap of 2D Na3Bi, significantly greater than room temperature, and its compatibility with silicon, make it a promising platform for topological transistors.


[1] M. Nadeem, I. Di Bernardo, X. Wang, M.S. Fuhrer, and D. Culcer, Nano Letters 21, 3155–3161 (2021).

[2] I. Di Bernardo, J. Hellerstedt, C. Liu, G. Akhgar, W. Wu, S.A. Yang, D. Culcer, S.-K. Mo, S. Adam, M.T. Edmonds, and M.S. Fuhrer, Adv. Mater. 2005897, 33 (2021)

[3] J.L. Collins, A. Tadich, W. Wu, L.C. Gomes, J.N.B. Rodrigues, C. Liu, J. Hellerstedt, H. Ryu, S. Tang, S.-K. Mo, S. Adam, S.A. Yang, M.S. Fuhrer & M.T. Edmonds, Nature 564, 390-394 (2018).

[4] C. Liu, D. Culcer, Z. Wang, M.T. Edmonds, and M.S. Fuhrer, Nano Letters 9, 6306 (2020).