一维介观环中持续电流的电子-声子相互作用非经典效应  

Non-classical state effect on the persistent current in one-dimensional mesoscopic ring with electron-phonon interaction

作　　者：罗质华[1] 梁国栋[2] 

机构地区：[1]广东第二师范学院物理系,广州510303 [2]暨南大学光电工程系,广州510632

出　　处：《物理学报》2011年第3期610-619,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10574163)资助的课题~~

摘　　要：基于声子相干态功效和计及声子压缩态非经典效应,研究了电子-磁振子和电子-声子相互作用对一维介观环持续电流的影响.与自由环比较,由于电子-磁振子相互作用,持续电流的振幅呈现指数减小.对于正常态电子,电子-声子相互作用导致持续电流以Debye-Waller(D-W)因子衰减.但是计入跳步电子-单声子相干态关联效应导致系统本征态能量大幅度下降,从而持续电流In有大幅度增加.另一方面计入双声子相干态行为,由于声子压缩态效应压缩电子-相干(态)声子弹性散射行为,导致电子绕环运动保持电子的相位相干性,使得D-W效应衰减有效减弱.特别是由于声子压缩-声子相干态之间非绝热关联效应的作用,压缩角极显著增大更有效压制D-W效应引起基态能量大幅度下降和持续电流有更大幅度增加.应当特别指出,持续电流随外界磁通变化出现周期性振荡,当外界磁通Φem=0时,本征持续电流～In≠0,系统仍会支持平衡自旋和电荷流,外界磁通只起到一个绝热参量作用.Based on the efficacy of the phonon coherent state and with consideration of the non-classical effect of the squeezed state of phonon,the influence of the electron-magnon interaction and the electron-phonon interaction on the persistent current in one-dimensional mesoscopic ring is studied. Compared with the free ring,our study shows that in one-dimensional mesoscopic ring,the amplitude of the persistent current exponentially diminishes due to the electron-magnon interaction. For the normal state electron,the interaction of the electron-phonon causes the persistent current to weakendce to the Debye-Waller effect. However,taking the correlation between the hopping electron states and the one-phonon coherent states into the equation,the ground energy of the mesoscopic system is declined in a large scale. In result,the persistent current In is increased substantially. On the other hand,taking the behavior of the two-phonon coherent state into account,as the effect of the squeezed states of phonons maintains the phase coherence of electrons,so the Debye-Waller attenuation is weakened effectively. Especially,when the squeezed angle is larger,because of the non-adiabatic correlation between the squeezed-phonon states and the coherent states of phonon,it causes a significant decline in the ground state energy and a significant increase in the squeezed angle,thus persistent current has a even more significant increase. It should be pointed out,that the persistent current shows period oscillation as the external magnetic flux changes. Even the external magnetic flux Φem = 0,still the persistent current of the intrinsic has ～I n≠0. The system continuoues to support the equilibrium spin and charge flow,the external magnetic flux only plays the role of an adiabatic parameter.

关 键 词：持续电流 电子-声子相互作用 声子相干态 声子压缩态效应 

分 类 号：O469[理学—凝聚态物理]