arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0806.1595cond-mat.mes-hall
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闭环干涉仪中Aharonov-Bohm振荡的拍频

Beating of Aharonov-Bohm oscillations in a closed-loop interferometer

Sanghyun Jo, Gyong Luck Khym, Dong-In Chang, Yunchul Chung, Hu-Jong Lee, Kicheon Kang, Diana Mahalu, Vladimir Umansky

摘要:

闭环型干涉仪的问题之一是Aharonov-Bohm(AB)振荡的跳动。最近的观测表明,在具有强自旋轨道相互作用(SOI)的材料中,这种拍频可能是由导电电子拾取Berry相位引起的。在这项研究中,我们还观察到拍的AB振荡的栅极定义的闭环干涉仪上制作的GaAs/AlGaAs二维电子气异质结。由于这种异质结构具有非常小的SOI,排除了贝里相位拾取的图像。在这项研究中的拍频的观察,形成一个单一的横向子带模式在我们的门定义的干涉仪的两个手臂的可控性,也排除了经常声称的多个横向子带效应。观察到周期为h/2 e的拍波的节点随侧门的变化呈现抛物线分布。这些结果被证明是很好的解释,而不诉诸SOI效应,在一个单一的横向子带中的二维多纵模的存在。测得的电导的傅立叶谱,尽管显示多个h/e峰与磁场的依赖性是非常相似的,从强SOI材料,也可以被解释为二维多纵模效应。

英文摘要:

One of the points at issue with closed-loop-type interferometers is beating in the Aharonov-Bohm (AB) oscillations. Recent observations suggest the possibility that the beating results from the Berry-phase pickup by the conducting electrons in materials with the strong spin-orbit interaction (SOI). In this study, we also observed beats in the AB oscillations in a gate-defined closed-loop interferometer fabricated on a GaAs/AlGaAs two-dimensional electron-gas heterostructure. Since this heterostructure has very small SOI, the picture of the Berry-phase pickup is ruled out. The observation of beats in this study, with the controllability of forming a single transverse subband mode in both arms of our gate-defined interferometer, also rules out the often-claimed multiple transverse subband effect. It is observed that nodes of the beats with an h/2e period exhibit a parabolic distribution for varying the side gate. These results are shown to be well interpreted, without resorting to the SOI effect, by the existence of two-dimensional multiple longitudinal modes in a single transverse subband. The Fourier spectrum of measured conductance, despite showing multiple h/e peaks with the magnetic-field dependence that are very similar to that from strong-SOI materials, can also be interpreted as the two-dimensional multiple-longitudinal-modes effect.

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