Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session Y43: Emerging Magnetic Topological Materials
8:00 AM–10:48 AM,
Friday, March 10, 2023
Room: Room 317
Sponsoring
Unit:
DMP
Chair: Shuyu Cheng, Ohio State University
Abstract: Y43.00013 : Towards the quantum spin Hall regime in (Bi1−xSbx)2Te3 ultrathin films*
10:24 AM–10:36 AM
Presenter:
Sofie Kölling
(University of Twente)
Authors:
Sofie Kölling
(University of Twente)
Feike van Veen
(University of Twente)
Roel M Metsch
(University of Twente)
Karola Neeleman
(University of Twente)
Daniel Rosenbach
(University of Cologne)
Inanc Adagideli
(Sabanci University)
Alexander Brinkman
(University of Twente)
gap at the Dirac point. Depending on film thickness, the nature of this gap oscillates between trivial and
inverted [1, 2]. When the chemical potential of such a thin film lies within an inverted hybridization gap,
the system will be in the quantum spin Hall (QSH) state, with two counterpropagating spin-momentum
locked channels along each edge.
Ultrathin (Bi1−xSbx)2Te3 is a candidate material, as tuning the Bi/Sb ratio moves the Dirac point into
the bulk band gap [3]. We optimize the morphology of ultrathin (Bi1−xSbx)2Te3 on Al2O3 substrates
by molecular beam epitaxy, by tuning both substrate temperature and vicinal angle. This leads to film
thicknesses expected to lie within the QSH regime.
The films are structured into micrometer-sized devices to perform both local and non-local transport
measurements at cryogenic temperatures. Due to the morphology of the films, we do not expect
a coherent percolation path between source and drain contacts. However, 1D contributions to the
conductivity can be extracted by comparing the scaling of features as a function of device geometry [4].
Based on this, we study the possibility of both 2D and 1D conductance based on electronic transport
data.
References:
[1] PRB 81, 041307 (2010)
[2] PRB 97, 075419 (2018)
[3] Nat Commun 2, 574 (2011)
[4] PRL 123, 047701 (2019)
*Lockheed Martin
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