带有电子-双声子相互作用的一维铁磁性介观环的非经典本征态和非经典本征持续电流  

Non-classical eigen state and the persistent current in one-dimensional mesoscopic ring with the electron-two-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》2012年第5期411-421,共11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：在一维铁磁性织构介观环的基础上,计及电子-双声子相互作用,介入了三项非经典效应抑制电子-单声子相互作用引起的量子涨落效应:1)跳步电子-单声子相干态关联效应;2)由压缩相干态引起的声子压缩态-单声子相干态间过程关联效应;3)声子位移-声子压缩态的表象关联效应.从结果来看,电子-双声子相互作用明显加强了压缩效应(增大压缩参量),而跳步电子-单声子相干态关联效应引起本征能量大幅度下降,持续电流大幅度增加.特别是介入了声子压缩态-单声子相干态间过程关联效应后,声子压缩参量远大于理想压缩态相应的压缩参量,有效地抑制了Debye-Waller(D-W)效应.当声子压缩态-单声子相干态间过程关联与声子位移重整化效应结合在一起时,声子场的压缩将更大幅度地增加,D-W效应(参量ωph)将更大幅度地减小,ωph■ω_ph^((0)),从而极大幅度地抑制了电子-单声子相互作用导致的量子涨落效应.这样一来,非经典态本征能量E_n极大幅度地下降,E_n■E_n^((0)),与此同时,本征持续电流振幅I_n则极大幅度地增大,I_n■I_n^((0)).For the one-dimensional mesoscopic ring with the ferromagnetic texture, to restrain the quantum fluctuations caused by the electron-one-phonon interaction, the non-classical correlation effects are used in our research to solve this puzzling problem, i.e. 1） the hopping electron-displaced phonon state correlation; 2） the process correlation between the phonon squeezed state, and the one-phonon coherent state, originating from the squeezed coherent state of phonon; 3） the renormalization of the phonon displacement. It is found that due to the electron-two phonon interaction, the squeezing effect of phonon is enhanced significantly. Because of the effect of the electron-displaced phonon correlation the non-classical eigen state energy declines significantly and the amplitude of the persistent current increases substantially. Particularly the process correlation between the squeezed phonon state and the one-phonon coherent state is by far the most important contribution to these non-classical effects. First of all, this effect more greatly increases the squeezing effect of phonon field in contrast to the ideal squeezed state. As a result, it will restrain effectively the Debye-Waller effect （factor ωph） with ωph （ ωph. Furthermore, when we combine the effective renormalization of the phonon displacement with the effect of process correlation between the phonon squeezed state and the one-phonon coherent state, the phonon squeezing effect will increases substantially, at the same time, the D-W effect decreased more substantially （ωph （≤ωph）, thereby weakening the quantum fluctuation to a bigger degree. With these results, the non-classical eigen energy （En） is much lowered （En≤En^（0）））, while the amplitude of eigen persistent current is increased most significantly （In≤ In^（0））.

关 键 词：非经典本征态 持续电流 电子-声子相互作用 压缩相干态 

分 类 号：O469[理学—凝聚态物理]