含杂质的三臂环中的持续电流  

The Persistent Currents in the Triple-arm Ring with an Impurity

作　　者：霍淑芬[1] 肖景林[1] 

机构地区：[1]内蒙古民族大学物理与电子信息学院,内蒙古通辽028043

出　　处：《发光学报》2009年第5期692-696,共5页Chinese Journal of Luminescence

基　　金：国家自然科学基金(10347004;10747002)资助项目

摘　　要：采用量子波导理论,研究了含杂质的介观三臂环中的持续电流。结果表明:输运电流存在时,不含磁场的三臂环中也可有持续电流产生,这是纯的量子现象。即使含杂质的三臂环和含杂质的单环上、下臂比例相同,两环中的电流也明显不同。更重要的是发现在某些能量范围内,杂质不总是制约持续电流的增大。Recently, development of fabrication techniques has made possible for the dimensions of a structure to be much smaller than its characteristic lengths, such as mean free path and phase-coherence length of an electron. Such structure is referred to as mesoscopic system. The physical properties of the mesoscopic system are so affected by quantum-interference effects strongly that this system exhibits many novel phenomena. One of the intriguing phenomena is the persistent current in quantum rings threaded by magnetic flux. Prior to the experimental observation, Btittiker, Imry and Landauer suggested that the existence of persistent current is in an ordered one-dimension ring threaded by magnetic flux. Since the discovery of the persistent current, there have been many studies on the single ring, coupled ring and multiple-arm ring structures. It was shown that, in the presence of a transport current, the persistent current can flow in a ring, even in the absence of a magnetic field. The purpose of this paper is to study persistent currents in the triple-arm ring with an impurity by using quantum waveguide theory. It was found that in the presence of the transport current the persistent current arises in such structure even in the absence of magnetic field, beside, the persistent current in the triplearm ring with an impurity and the single ring with an impurity are different, even though the ratio of the upper arm to the lower arm is same for the two cases. More importantly, It was shown that the impurity does not always suppress the amplitude of persistent current at some energy ranges.

关 键 词：量子波导理论 δ函数杂质 持续电流 

分 类 号：O469[理学—凝聚态物理] O472.4[理学—电子物理学]