Matsuo Sadashige, Takeshita Shunpei, Tanaka Takahiro, Nakaharai Shu, Tsukagoshi Kazuhito, Moriyama Takahiro, Ono Teruo, Kobayashi Kensuke
Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Nat Commun. 2015 Sep 4;6:8066. doi: 10.1038/ncomms9066.
Massless Dirac electron systems such as graphene exhibit a distinct half-integer quantum Hall effect, and in the bipolar transport regime co-propagating edge states along the p-n junction are realized. Additionally, these edge states are uniformly mixed at the junction, which makes it a unique structure to partition electrons in these edge states. Although many experimental works have addressed this issue, the microscopic dynamics of electron partition in this peculiar structure remains unclear. Here we performed shot-noise measurements on the junction in the quantum Hall regime as well as at zero magnetic field. We found that, in sharp contrast with the zero-field case, the shot noise in the quantum Hall regime is finite in the bipolar regime, but is strongly suppressed in the unipolar regime. Our observation is consistent with the theoretical prediction and gives microscopic evidence that the edge states are uniquely mixed along the p-n junction.
诸如石墨烯之类的无质量狄拉克电子系统表现出独特的半整数量子霍尔效应，并且在双极输运 regime 中，沿 p-n 结共传播的边缘态得以实现。此外，这些边缘态在结处均匀混合，这使其成为在这些边缘态中对电子进行划分的独特结构。尽管许多实验工作已经解决了这个问题，但在这种特殊结构中电子划分的微观动力学仍然不清楚。在这里，我们在量子霍尔 regime 以及零磁场下对结进行了散粒噪声测量。我们发现，与零场情况形成鲜明对比的是，量子霍尔 regime 中的散粒噪声在双极 regime 中是有限的，但在单极 regime 中受到强烈抑制。我们的观察结果与理论预测一致，并给出了微观证据，证明边缘态沿 p-n 结独特地混合。
