Journal Article Edge mixing dynamics in graphene p-n junctions in the quantum Hall regime

Matsuo, Sadashige  ,  Takeshita, Shunpei  ,  Tanaka, Takahiro  ,  Nakaharai, Shu  ,  Tsukagoshi, Kazuhito  ,  Moriyama, Takahiro  ,  Ono, Teruo  ,  Kobayashi, Kensuke

62015-09-04 , Nature Publishing Group
注目物質「グラフェン」における電子の分配を世界で初観測 -電子の波動性を利用した電子干渉デバイスの実現へ-. 京都大学プレスリリース. 2015-09-08.
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.

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