Measurement of spin transport properties and spin coherence in molecular semiconductors

这个项目的目的是精确地估计分子半导体中的自旋相干性。在项目的第一阶段，我从意大利的一个合作者(V.Dediu博士)那里得到了一个分子自旋阀装置，并试图测量分子半导体中传播的自旋的自旋进动，这被称为Hanle效应。然而，由于自旋注入设备中的分子的可靠性较低，因此没有观察到这样的效果。在第二阶段，除了寻找一种新的氧化物铁磁材料作为分子半导体的良好自旋源外，还对分子半导体单晶与铁磁金属之间的界面电子结构和电子结构的调制进行了实验研究。这两项工作都进行得很成功。在最后阶段，引入了一种新的自旋注入方法--动态自旋泵浦，并成功地实现了对零禁带分子半导体单层石墨烯的自旋注入，并精确测量了自旋相干性。这个项目揭示了早期分子自旋电子学研究中存在的严重问题，并使一种新的自旋注入方法得以建立到分子半导体中。

The purpose of this project is to estimate spin coherence in molecular semiconductors precisely. In the first stage of the project, I was provided a molecular spin valve device from a collaborator in Italy (Dr. V. Dediu) and tried to measure spin precession of propagating spins in molecular semiconductors, which is called as Hanle effect. However, no such effect was observed due to less reliability of spin injection into molecules in the device. He nce, in the second stage, experimental investigations of an interfacial electronics structures between molecular semiconductor single crystal and ferromagnetic metals and modulation of the electronic structure were implemented, in addition to a search for a new oxide ferromagnet as a good spin source for molecular semiconductors. Both were successfully carried out. In the final stage, a new spin injection method, dynamical spin pumping, was introduced, and spin injection into a zero-gap molecular semiconductor, single-layer graphene, was successfully demonstrated and spin coherence was precisely measured. This project revealed serious problems in earlier studies of molecular spintronics, and enabled an establishment of a novel spin injection method into molecular semiconductors.