Wave packet dynamics in semiconductor quantum rings of finite width

作     者：Andrey Chaves G. A. Farias F. M. Peeters B. Szafran 

作者机构：Departamento de Física Universidade Federal do Ceará Caixa Postal 6030 Campus do Pici 60455-900 Fortaleza Ceará Brazil Department of Physics University of Antwerp Groenenborgerlaan 171 B-2020 Antwerp Belgium Faculty of Physics and Applied Computer Science AGH University of Science and Technology al. Mickiewicza 30 30-059 Kraków Poland 

出 版 物：《Physical Review B》 (物理学评论B辑：凝聚态物质与材料物理学)

年 卷 期：2009年第80卷第12期

页      面：125331-125331页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

摘      要：The time evolution of a wave packet injected into a semiconductor quantum ring is investigated in order to obtain the transmission and reflection probabilities. Within the effective-mass approximation, the time-dependent Schrödinger equation is solved for a system with nonzero width of the ring and leads and finite potential-barrier heights, where we include smooth lead-ring connections. In the absence of a magnetic field, an analysis of the projection of the wave function over the different subband states shows that when the injected wave packet is within a single subband, the junction can scatter this wave packet into different subbands but remarkably at the second junction the wave packet is scattered back into the subband state of the incoming wave packet. If a magnetic field is applied perpendicularly to the ring plane, transmission and reflection probabilities exhibit Aharonov-Bohm (AB) oscillations and the outgoing electrons may end up in different subband states from those of the incoming electrons. Localized impurities, placed in the ring arms, influence the AB oscillation period and amplitude. For a single impurity or potential barrier of sufficiently strong strength, the period of the AB oscillations is halved while for two impurities localized in diametrically opposite points of the ring, the original AB period is recovered. A theoretical investigation of the confined states and time evolution of wave packets in T wires is also made, where a comparison between this system and the lead-ring junction is drawn.