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Nano-optical spin electronics based on near-field optical microscopic technique

基于近场光学显微技术的纳米光学自旋电子学

基本信息

批准号：
14076206
负责人：
SAIKI Toshiharu
金额：
$ 12.61万
依托单位：
Keio Univesity
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

As well as the control of interband-polarization coherence, the storage and manipulation of spin coherence is of great importance in spintronics. The quantum confinement of electrons is advantageous for spintronics in terms of the control of spin behavior through the optimization of spin lifetime and g-factor. For local injection, control, and detection of spin-polarized electrons in individual quantum structures, optical spin manipulation with the near-field light source is needed.We have established a near-field scanning optical microscope (NSOM) system to measure and manipulate the spin state of a single quantum dot (QD) with a high spatiotemporal resolution under a magnetic field up to 5T. The spatial resolution as high as 30-50 nm enabled us to visualize wave functions of quantum-confined excitons.Owing to the high spatial resolution of our NSOM, the shape of the QD is clearly visualized. From magneto-PL spectroscopy of a single QD, a diamagnetic shift of the exciton emission was observed. Referring to the theoretical value we estimate the size of the QD from a diamagnetic coefficient, which is determined by the Bohr radius of excitons confined in QDs. The result was in good agreement with that obtained by the real-space NSOM mapping.We also built a near-field optical microscope for polarization spectroscopy in the reflection configuration. Polarization properties of good quality and stability as well as high optical throughput allows high-sensitive magneto-optical spectroscopy with high spatial resolution. Kerr-rotation imaging of magnetic domains in garnet thin films and depolarization microscopy of a phase-change material with a spatial resolution of 30 nm are demonstrated.

在自旋电子学中，除了带间极化相干的控制外，自旋相干的存储和操纵也是非常重要的。电子的量子限制对于自旋电子学而言是有利的，因为通过优化自旋寿命和g因子来控制自旋行为。为了实现自旋极化电子在单个量子结构中的局域注入、控制和探测，需要利用近场光源对自旋进行光学操控，我们建立了一套近场扫描光学显微镜（NSOM）系统，在高达5 T的磁场下对单个量子点（QD）的自旋进行了高时空分辨率的测量和操控。高达30-50 nm的空间分辨率使我们能够可视化量子限制激子的波函数。由于我们的NSOM的高空间分辨率，QD的形状被清晰地可视化。从单量子点的磁光致发光光谱，观察到的激子发射的抗磁位移。参考理论值，我们估计的量子点的大小从抗磁性系数，这是由限制在量子点的激子的玻尔半径。实验结果与实空间NSOM映射结果吻合较好。我们还搭建了一台反射式近场光学显微镜。良好的质量和稳定性以及高的光通量的偏振特性允许具有高空间分辨率的高灵敏度磁光光谱。证明了石榴石薄膜中磁畴的克尔旋转成像和相变材料的退偏振显微镜，空间分辨率为30 nm。