Spin depolarization dynamics of WSe2 bilayer

• 来源期刊: 中国物理B（英文版）
• 关键词: spin depolarization dynamics WSe2 bilayer time-resolved Kerr rotation
• 年，卷（期）: 2018,（5）
• 页码范围: 447-452
• 页数: 6页
• 语种: 英文
• DOI: 10.1088/1674-1056/27/5/057202

摘要

In this work,the spin dynamics of a centrosymmetric WSe2 bilayer has been investigated by the two-color timeresolved Kerr rotation together with helicity-resolved transient reflectance techniques.Two depolarization processes associated with the direct transition are discovered at a low temperature of 10 K,with the characteristic decaying time of ～3.8 ps and ～20 ps,respectively.The short decay time of ～3.8 ps is suggested to be the exciton spin lifetime of the WSe2 bilayer,which is limited by the short exciton lifetime of the WSe2 bilayer and the rapid intervalley electron-hole exchange interaction between K+ and K-valley in the same layer as that of monolayer.The long decay time of ～20 ps is suggested to be the spin lifetime of photo-excited electrons,whose spin relaxation is governed by the rapid intervalley scattering from the K valley to the global minimum Σ valley and the subsequent interlayer charge transfer in WSe2 bilayer.Our experimental results prove the existence of the spin-polarized excitons and carriers even in centrosymmetric transition metal dichalcogenides (TMDCs) bilayers,suggesting their potential valleytronic and spintronic device applications.