Jiang Chongyun, Xu Weigao, Rasmita Abdullah, Huang Zumeng, Li Ke, Xiong Qihua, Gao Wei-Bo
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.
NOVITAS, Nanoelectronics Center of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
Nat Commun. 2018 Feb 21;9(1):753. doi: 10.1038/s41467-018-03174-3.
Transition metal dichalcogenides have valley degree of freedom, which features optical selection rule and spin-valley locking, making them promising for valleytronics devices and quantum computation. For either application, a long valley polarization lifetime is crucial. Previous results showed that it is around picosecond in monolayer excitons, nanosecond for local excitons and tens of nanosecond for interlayer excitons. Here we show that the dark excitons in two-dimensional heterostructures provide a microsecond valley polarization memory thanks to the magnetic field induced suppression of valley mixing. The lifetime of the dark excitons shows magnetic field and temperature dependence. The long lifetime and valley polarization lifetime of the dark exciton in two-dimensional heterostructures make them promising for long-distance exciton transport and macroscopic quantum state generations.
过渡金属二硫族化合物具有谷自由度，其具有光学选择规则和自旋-谷锁定特性，这使得它们在谷电子学器件和量子计算方面具有广阔前景。对于这两种应用而言，长的谷极化寿命至关重要。先前的结果表明，单层激子中的谷极化寿命约为皮秒，局域激子为纳秒级，层间激子为几十纳秒。在此我们表明，二维异质结构中的暗激子由于磁场诱导的谷混合抑制而提供了微秒级的谷极化记忆。暗激子的寿命表现出磁场和温度依赖性。二维异质结构中暗激子的长寿命和谷极化寿命使其在长距离激子输运和宏观量子态产生方面具有广阔前景。
