Valley depolarization in monolayer WSe2.
Valley depolarization in monolayer WSe2.
复制标题
单层 WSe2 的谷去极化
DOI：
10.1038/srep15625
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发表时间：
2015-10-22
影响因子：
4.6
通讯作者：
Zhang X
中科院分区：
文献类型：
--
作者：
Yan T;Qiao X;Tan P;Zhang X
我们系统地研究了单层WSe_2在不同温度、不同激发能量和不同激子密度下的圆极化。实验证实，WSe_2中的谷退极化是由谷间电子-空穴交换相互作用控制的。更重要的是，观察到了激子谷圆极化与激发功率密度的非单调关系，为激子谷间散射率与激发激子密度的非单调关系提供了实验依据。我们实验观测的物理起源被认为类似于在传统的GaAs量子井系统中工作的D‘yakonov-Perel’机制。我们的实验结果对于更好地理解原子薄过渡金属二卤化物中的谷伪自旋弛豫具有重要意义。
We have systematically examined the circular polarization of monolayer WSe2 at different temperature, excitation energy and exciton density. The valley depolarization in WSe2 is experimentally confirmed to be governed by the intervalley electron-hole exchange interaction. More importantly, a non-monotonic dependence of valley circular polarization on the excitation power density has been observed, providing the experimental evidence for the non-monotonic dependence of exciton intervalley scattering rate on the excited exciton density. The physical origination of our experimental observations has been proposed to be in analogy to the D′yakonov-Perel′ mechanism that is operative in conventional GaAs quantum well systems. Our experimental results are fundamentally important for well understanding the valley pseudospin relaxation in atomically thin transition metal dichalcogenides.