Kondo effect and spin manipulation in quantum dot complex systems

量子点是在半导体上制造的纳米尺度的盒子，通常被称为人造原子。自旋为1/2的人造原子将近藤效应显示为金属中的磁性杂质。在这个项目中，理论上研究了嵌入量子点、耦合量子点或人造分子、存在强自旋-轨道相互作用的量子点等小环中的近藤效应。因此，在这个多体问题中揭示了新的物理。半导体纳米结构(如人造原子)的自旋操纵是量子计算机和自旋电子学应用的重要问题。我们开展了自旋注入和隧道磁阻的基础研究。

Quantum dots, boxes of nanometer scale fabricated on semiconductors, are often called artificial atoms. Artificial atoms with spin 1/2 show the Kondo effect as magnetic impurities in metals. In this project, the Kondo effect has been theoretically examined in a small ring with an embedded quantum dot, coupled quantum dots or artificial molecules, quantum dot in the presence of strong spin-orbit interaction, etc. In consequence, new physics has been revealed in this many-body problem. Spin manipulation in semiconductor nano-structures such as artificial atoms is an important issue for the application to quantum computers and spintronics. We have developed the fundamental researches for the spin injection and tunnel magnetoresistance.