Abstract
We report on the fabrication of a two-dimensional topological insulator Bi(111) bilayer on Sb nanofilms via a sequential molecular beam epitaxy growth technique. Our angle-resolved photoemission measurements demonstrate the evolution of the electronic band structure of the heterostructure as a function of the film thickness and reveal the existence of a two-dimensional spinful massless electron gas within the top Bi bilayer. Interestingly, our first-principles calculation extrapolating the observed band structure shows that, by tuning down the thickness of the supporting Sb films into the quantum dimension regime, a pair of isolated topological edge states emerges in a partial energy gap at 0.32 eV above the Fermi level as a consequence of quantum confinement effect. Our results and methodology of fabricating nanoscale heterostructures establish the Bi bilayer/Sb heterostructure as a platform of great potential for both ultra-low-energy-cost electronics and surface-based spintronics.
| Original language | English |
|---|---|
| Pages (from-to) | 3859-3864 |
| Number of pages | 6 |
| Journal | ACS Nano |
| Volume | 10 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 22 2016 |
| Externally published | Yes |
Funding
This work was supported by the U.S. Department of Energy (DOE), Office of Science (OS), Office of Basic Energy Sciences, under Grant No. DE-FG02-07ER46383 (T.-C.C.), DE-FG02-04ER46148 (F.L., Z.W.), DE-FG02-05ER46200 (M.Z.H.), NSF-MRSEC Grant No. DMR-1121252 (Z.W.), the National Science Foundation of China under Grant No. 11204133 (X.W.), the Jiangsu Province Natural Science Foundation of China under Grant No. BK2012393 (X.W.), and the Young Scholar Project of Nanjing University of Science and Technology (X.W.). Work at Princeton is funded in part by the Gordon and Betty Moore Foundation?s EPiQS Initiative through Grant GBMF4547. The theoretical work is conducted at University of Utah using the CHPC and NERSC computing resources. We thank M. Bissen and M. Severson for assistance with beamline operation at the Synchrotron Radiation Center, which was supported by the University of Wisconsin - Madison. T.M. and the beamline operations were partially supported by NSF Grant No. DMR 13-05583.
| Funders | Funder number |
|---|---|
| NSF-MRSEC | DMR-1121252 |
| National Science Foundation | DMR 13-05583 |
| U.S. Department of Energy | |
| Gordon and Betty Moore Foundation | GBMF4547 |
| Office of Science | |
| Basic Energy Sciences | DE-FG02-05ER46200, DE-FG02-04ER46148, DE-FG02-07ER46383 |
| University of Wisconsin-Madison | |
| National Natural Science Foundation of China | 11204133 |
| Natural Science Foundation of Jiangsu Province | BK2012393 |
| Nanjing University of Science and Technology |
Keywords
- Bi(111) bilayer
- Kane-Mele model
- quantum spin Hall effect
- quantum well states