贵金属/半导体异质结中的光致自旋电流效应研究

Study on the mechanism of photoinduced spin current effect in noble metal/semiconductor heterojunction

自旋电子材料因能同时对电子的自旋和电荷两个自由度实施操控,在构筑以低功耗、超高速、大容量和超宽带为特征的新一代信息处理技术中展现出巨大的应用潜力.然而,通过掺杂过渡金属元素和稀土离子而形成的传统稀磁半导体和钙钛矿锰氧化物往往因结构缺陷导致的居里温度不高、自旋磁矩和自旋极化率偏低等不足,阻碍了自旋电子材料的商业化应用.近年来,在高纯半导体上沉积贵金属薄膜所形成的贵金属/半导体异质结中,通过使用偏振光激发该类异质结可产生纯自旋电流.这种基于逆自旋霍尔效应(ISHE)、可在室温下运行的、非接触和非破坏型的自旋极化激励方法理论上可获得高于50%自旋极化率,引起了人们的广泛关注.文章主要介绍光致自旋电流形成机制和测试方法,以及入射光圆偏振度、光强、入射角度等参数对光致自旋注入效率的调控机理,介绍杂质介导和声子介导对光致自旋输运的贡献,最后提出增强光致自旋电子极化率的可行方案,可为揭示自旋载流子产生、注入和输运相关的自旋动力学核心科学问题以及研制高性能自旋电子器件提供有益的参考.

Spintronic materials show great application potential in building a new generation of information processing technology characterized by low power consumption,ultra-high speed,large capacity and ultra wide band,because they can control the two degrees of freedom of electron spin and charge at the same time.However,the traditional diluted magnetic semiconductors and perovskite manganese oxides formed by doping transition metals and rare earth ions often hinder the commercial application of spintronics due to low Curie temperature,low spin magnetic moment and low spin polarization caused by structural defects.In recent years,pure spin current can be generated by using polarized light to excite noble metal/semiconductor heterojunction formed by depositing noble metal films on high-purity semiconductors.Based on the inverse spin Hall effect(ISHE),this non-contact and non-destructive spin polarization excitation method,which can operate at room temperature,can theoretically obtain spin polarizability higher than 50%,which has attracted widespread attention.This paper mainly introduces the formation mechanism and testing method of the photo induced spin current,and the regulation mechanism of the circular polarization degree,light intensity,incident angle and other parameters of the incident light on the photo induced spin injection efficiency.The contribution of impurity mediated and phonon mediated to photoinduced spin transport is introduced.Finally,a feasible scheme to improve the polarization of photoinduced spintronics is proposed.This paper can provide an effective reference for revealing the core scientific problems of spin dynamics related to the generation,injection and transport of spin carriers and developing high-performance spintronic devices.