Ren Ya-Ning, Zhuang Yu-Chen, Sun Qing-Feng, He Lin
Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China.
International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
Phys Rev Lett. 2022 Aug 12;129(7):076802. doi: 10.1103/PhysRevLett.129.076802.
Introducing quantum confinement has uncovered a rich set of interesting quantum phenomena and allows one to directly probe the physics of confined (quasi-)particles. In most experiments, however, an electrostatic potential is the only available method to generate quantum dots in a continuous system to confine (quasi-)particles. Here we demonstrate experimentally that inhomogeneous pseudomagnetic fields in strained graphene can introduce exotic quantum confinement of massless Dirac fermions. The pseudomagnetic fields have opposite directions in the two distinct valleys of graphene. By adding and tuning real magnetic fields, the total effective magnetic fields in the two valleys are imbalanced. By that we realized valley-contrasting spatial confinement, which lifts the valley degeneracy and results in field-tunable valley-polarized confined states in graphene. Our results provide a new avenue to manipulate the valley degree of freedom.
引入量子限制揭示了一系列丰富有趣的量子现象，并使人们能够直接探究受限（准）粒子的物理特性。然而，在大多数实验中，静电势是在连续系统中产生量子点以限制（准）粒子的唯一可用方法。在此，我们通过实验证明，应变石墨烯中的非均匀赝磁场可以引入无质量狄拉克费米子的奇异量子限制。赝磁场在石墨烯的两个不同能谷中方向相反。通过添加和调节真实磁场，两个能谷中的总有效磁场变得不平衡。借此我们实现了谷对比空间限制，这消除了谷简并，并在石墨烯中产生了场可调谐的谷极化受限态。我们的结果为操纵谷自由度提供了一条新途径。
