相互作用量子点系统中的场致自旋电流.pdfVIP

研究快讯 相互作用量子点系统中的场致自旋电流 1 1 , 2 张 　平 　　薛其坤 　　谢心澄 ( 1 　中国科学院物理研究所　国际量子结构中心　北京　100080) (2 　Department of Physics , Oklahoma State University , USA ) 摘　要 　　从理论上研究了相互作用量子点在外部旋转磁场下的非平衡自旋输运性质. 研究结果表明 ,量子点中 的相干自旋振荡可以导致自旋电流的产生. 当计入库仑关联相互作用后 ,近藤共振效应受外部进动磁场的影响很 强. 特别是当磁场的进动频率与塞曼能移满足共振条件时 ,每个自旋近藤峰就会劈裂为两个自旋共振峰的叠加. 在 低温强耦合区 ,这种近藤型共隧穿过程对自旋电流带来重要贡献. 关键词 　　量子点 ,近藤共振 , 自旋电流, 自旋电子学,量子计算 Spin current through a quantum dot in the presence of an oscillating magnetic field 1 1 , 2 ZHANG Ping 　　XUE QiKun 　　XIE XinCheng ( ) 1 　International Centerfor Quantum Structures , Institute of Physics , Chinese Academy of Sciences , Beijing 　100080, China (2 　Department of Physics , Oklahoma State University , USA ) Abstract 　　Nonquilibrium spin transport through an interacting quantum dot is discussed. The coherent spin oscil lations in the dot provide a source for generating spin current. In the interaction regime , the Kondo effect is influ enced significantly by the presence of a precessing magnetic field. In particular , when the precession frequency is tuned to resonance between the spinup and spindown states of the dot , the Kondo singularity for each spin splits into a superposition of two resonance peaks. The Kondotype cotunneling contribution is manifested by a large enhance ment of the pumped spin current in the strong coupling , low temperature regime. Key words 　　quantum dot , Kon