期刊
PHYSICAL REVIEW B
卷 79, 期 8, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.79.085407
关键词
band structure; bound states; carbon; Dirac equation; Landau levels; nanostructured materials; quantum dots; quantum theory
资金
- Dutch Science Foundation NWO/FOM
- Swiss National Science Foundation (NSF-CH) [PP002-106310]
- German Research Foundation (DFG) via Forschergruppe [FOR 912]
- German Research Foundation (DFG) [Tr950/1-1]
The magnetic field dependence of energy levels in gapped single-layer and bilayer graphene quantum dots (QDs) defined by electrostatic gates is studied analytically in terms of the Dirac equation. Due to the absence of sharp edges in these types of QDs, the valley degree of freedom is a good quantum number. We show that its degeneracy is efficiently and controllably broken by a magnetic field applied perpendicular to the graphene plane. This opens up a feasible route to create well-defined and well-controlled spin and valley qubits in graphene QDs. We also point out the similarities and differences in the spectrum between single-layer and bilayer graphene quantum dots. Striking in the case of bilayer graphene is the anomalous bulk Landau level (LL) that crosses the gap, which results in crossings of QD states with this bulk LL at large magnetic fields in stark contrast to the single-layer case where this LL is absent. The tunability of the gap in the bilayer case allows us to observe different regimes of level spacings directly related to the formation of a pronounced sombrero in the bulk band structure. We discuss the applicability of such QDs to control and measure the valley isospin and their potential use for hosting and controlling spin qubits.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据