Recently, monolayer Tl on a Si or Ge substrate has been proposed for potential valleytronic systems. However, the band gaps of these systems are less than 0.1 eV, which is too small to be applied because an electric field or magnetic doping will reduce the band gaps further for the systems to become metallic. Here, we investigate SiC as an alternative substrate. By first-principles calculations we demonstrate that monolayer Tl can be grown on SiC. There are two valleys around the K/K′ points and the Berry curvature shows that the two valleys are inequivalent, indicating valley pseudospin. Moreover, due to the larger band gap of SiC (3.3 eV), the band gap of the Tl/SiC system is 0.6 eV, which is large enough for valley manipulation. Furthermore, we demonstrate that Cr doping can achieve valley polarization. Our study shows that the Tl/SiC system is promising for valleytronic applications.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was financially supported by the National Natural Science Foundation of China (No. 11504169, 61575094 and 21673118), the National Basic Research Program of China (2015CB932200) and the Jiangsu Qing Lan Project, the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province, China (16KJB150018). The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST).