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arXiv 1106.3535cond-mat.mes-hall
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石墨烯与门控混沌量子点的共振散射

Resonant scattering in graphene with a gate-defined chaotic quantum dot

Martin Schneider, Piet W. Brouwer

摘要:

我们研究了未掺杂的石墨烯片与两个金属接触和静电门控岛(量子点)之间的接触的电导。我们的分析是基于矩阵格林函数形式主义,最近由Titov { \em et al.} [物理学]修订版本\ Lett. { \bf 104},076802(2010)]。我们发现一个体育场形的点(具有混沌的经典动力学)和一个圆盘形的点(具有可积的经典动力学)的限制,点的大小是小的接触之间的距离的情况下之间的显着差异。特别地,对于体育场形的点的两端电导示出了作为栅极电压的函数的法诺共振,其仅在完全分离的共振的限制下交叉到Breit-Wigner共振,而对于盘形的点,由更高的角动量产生的尖锐的Breit-Wigner共振始终存在。

英文摘要:

We investigate the conductance of an undoped graphene sheet with two metallic contacts and an electrostatically gated island (quantum dot) between the contacts. Our analysis is based on the Matrix Green Function formalism, which was recently adapted to graphene by Titov {\em et al.} [Phys.\ Rev.\ Lett.\ {\bf 104}, 076802 (2010)]. We find pronounced differences between the case of a stadium-shaped dot (which has chaotic classical dynamics) and a disc-shaped dot (which has integrable classical dynamics) in the limit that the dot size is small in comparison to the distance between the contacts. In particular, for the stadium-shaped dot the two-terminal conductance shows Fano resonances as a function of the gate voltage, which cross-over to Breit-Wigner resonances only in the limit of completely separated resonances, whereas for a disc-shaped dot sharp Breit-Wigner resonances resulting from higher angular momentum remain present throughout.

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