Fractional Quantum Hall States in Bilayer Graphene Probed by Transconductance Fluctuations

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• 作者：Youngwook Kim ; Dong Su Lee ; Suyong Jung ; Viera Sk谩kalov谩 ; T. Taniguchi ; K. Watanabe ; Jun Sung Kim ; Jurgen H. Smet
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：November 11, 2015
• 年：2015
• 卷：15
• 期：11
• 页码：7445-7451
• 全文大小：428K
• ISSN：1530-6992

文摘

We have investigated fractional quantum Hall (QH) states in Bernal-stacked bilayer graphene using transconductance fluctuation measurements. A variety of odd-denominator fractional QH states with 谓_QH 鈫?谓_QH + 2 symmetry, as previously reported, are observed. However, surprising is that also particle-hole symmetric states are clearly resolved in the same measurement set. We attribute their emergence to the reversal of orbital states in the octet level scheme induced by a strong local charge imbalance, which can be captured by the transconductance fluctuations. Also the even-denominator fractional QH state at filling 鈭?/2 is observed. However, contrary to a previous study on a suspended graphene layer [Ki et al. Nano Lett.2014, 14, 2135], the particle-hole symmetric state at filling 1/2 is detected as well. These observations suggest that the stability of both odd and even denominator fractional QH states is very sensitive to local transverse electric fields in bilayer graphene.