论文标题
栅极控制双层石墨烯量子点中的电子孔跨界
Electron-hole crossover in gate-controlled bilayer graphene quantum dots
论文作者
论文摘要
间隙双层石墨烯中的电子和孔Bloch状态显示拓扑轨道磁矩，带有相反的符号在带边缘，这允许在平面外磁场中进行可调谷极化。这种内在特性使双层石墨烯中的电子和孔量子点（QD）有趣地用于山谷和旋转瓦利Qub。在这里，我们显示了双层石墨烯QD中电子孔交叉的测量值，证明了与浆果曲率相关的轨道磁矩的相反迹象。使用三层金属顶门，我们独立控制QD的隧道屏障，同时将职业从几洞态度调整为少数电子政权，越过位移场受控的带隙。频带间隙约为25 MEV，而电子和孔点的充电能在3-5 MEV之间。提取的山谷G因子约为17，在中等B场处的电子和孔状态的相对山谷极化。我们的测量值与我们设备的紧密结合计算很好。
Electron and hole Bloch states in gapped bilayer graphene exhibit topological orbital magnetic moments with opposite signs near the band edges, which allows for tunable valley-polarization in an out-of-plane magnetic field. This intrinsic 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 the opposite sign of the orbital magnetic moments associated with the Berry curvature. Using three layers of metallic top gates, we independently control the tunneling barriers of the QD 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 3-5 meV. The extracted valley g-factor is around 17 and leads to opposite valley polarization for electron and hole states at moderate B-fields. Our measurements agree well with tight-binding calculations for our device.
