论文标题
等离子体到半导体 - 金属杂种结构中的激子自旋转换
Plasmon to exciton spin conversion in semiconductor-metal hybrid structures
论文作者
论文摘要
电子旋转的光学控制是超快旋转型的基础：圆极化光与电子状态的自旋轨道耦合结合使用，可以在凝结物质中进行自旋操作。但是，常规方法仅限于沿一个特定方向的旋转方向，该方向由光子传播的方向决定。等离子间开放了新的功能，可以在纳米级的光线上量身定制光线极化。在这里，我们证明了通过等离子体的飞秒时间尺度上电子自旋的超快速光激发，以激发激子转化。通过在混合（CD，MN）TE量子井结构中覆盖有金属光栅的THZ自旋动力学，我们明确地确定光激发电子旋转的方向，该旋转锁定在锁定到表面plasmon polarlitons的传播方向上。使用入射光子的自旋作为额外的自由度，可以在二维平面以随意定向光激发的电子自旋。
Optical control of electronic spins is the basis for ultrafast spintronics: circularly polarized light in combination with spin-orbit coupling of the electronic states allows for spin manipulation in condensed matter. However, the conventional approach is limited to spin orientation along one particular orientation that is dictated by the direction of photon propagation. Plasmonics opens new capabilities, allowing one to tailor the light polarization at the nanoscale. Here, we demonstrate ultrafast optical excitation of electron spin on femtosecond time scales via plasmon to exciton spin conversion. By time-resolving the THz spin dynamics in a hybrid (Cd,Mn)Te quantum well structure covered with a metallic grating, we unambiguously determine the orientation of the photoexcited electron spins which is locked to the propagation direction of surface plasmon-polaritons. Using the spin of the incident photons as additional degree of freedom, one can orient the photoexcited electron spin at will in a two-dimensional plane.
