期刊
NANO LETTERS
卷 20, 期 10, 页码 7709-7715出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.0c03227
关键词
quantum dot; bilayer graphene; electron-hole crossover
类别
资金
- European Union [881603]
- European Research Council (ERC) [820254]
- Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy-Cluster of Excellence Matter and Light for Quantum Computing (ML4Q) through DFG [EXC 2004/1-390534769, STA 1146/11-1]
- Helmholtz Nano Facility
- FWF [I-3827]
- WWTF [MA14-002]
- Elemental Strategy Initiative by the MEXT, Japan [JPMXP0112101001]
- JSPS KAKENHI [JP20H00354]
- CREST, JST [JPMJCR15F3]
- European Research Council (ERC) [820254] Funding Source: European Research Council (ERC)
Electron and hole Bloch states in bilayer graphene exhibit topological orbital magnetic moments with opposite signs, which allows for tunable valley-polarization in an out-of-plane magnetic field. This property makes electron and hole quantum dots (QDs) in bilayer graphene interesting for valley and spin-valley qubits. Here, we show measurements of the electron-hole crossover in a bilayer graphene QD, demonstrating opposite signs of the magnetic moments associated with the Berry curvature. Using three layers of top gates, we independently control the tunneling barriers while tuning the occupation from the few-hole regime to the few-electron regime, crossing the displacement-field-controlled band gap. The band gap is around 25 meV, while the charging energies of the electron and hole dots are between 3 and 5 meV. The extracted valley g-factor is around 17 and leads to opposite valley polarization for electrons and holes at moderate B-fields. Our measurements agree well with tight-binding calculations for our device.
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