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Quantum Transport in Air-Stable Na3Bi Thin Films
Chang Liu1,2,3, Golrokh Akhgar1,3,4, James L Collins1,2,3
1School of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia.
ACS Applied Materials & Interfaces
|August 19, 2020
Summary
Researchers developed air-stable sodium bismuth (Na3Bi) thin films using protective capping layers. This breakthrough overcomes extreme air sensitivity, enabling easier experimental manipulation and preserving the material's unique topological properties.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Topological Materials
Background:
- Sodium bismuth (Na3Bi) is a material of interest as a 3D topological Dirac semimetal and 2D topological insulator.
- Its extreme air sensitivity hinders experimental studies, especially for thin films, confining research to ultrahigh vacuum.
Purpose of the Study:
- To develop air-stable Na3Bi thin films.
- To enable broader experimental investigation of Na3Bi thin films outside of ultrahigh vacuum conditions.
- To preserve the topological and transport properties of Na3Bi films upon air exposure.
Main Methods:
- Growth of Na3Bi thin films using molecular beam epitaxy.
- Application of magnesium difluoride (MgF2) or silicon (Si) capping layers for passivation.
- Electrical transport measurements in ultrahigh vacuum and after air exposure.
- Quantum transport measurements in a high-magnetic field cryostat.
Main Results:
- Na3Bi thin films passivated with MgF2 or Si exhibit stability in air.
- MgF2 or Si capping layers minimally affect Na3Bi transport properties in vacuum.
- Passivated films remain metallic for over 100 hours after air exposure, unlike unpassivated films.
- Quantum transport measurements confirm the retention of Dirac semimetal character after air exposure.
Conclusions:
- MgF2 or Si passivation effectively stabilizes Na3Bi thin films against air degradation.
- Air-stable Na3Bi films facilitate advanced characterization techniques, including quantum transport measurements.
- This work broadens the accessibility of Na3Bi for research and potential applications.
