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arXiv 1612.03414cond-mat.mes-hall
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半填充时石墨烯分数量子霍尔态中的复合费米子:狄拉克复合费米子的证据

Composite fermions in graphene fractional quantum Hall state at half filling: evidence for Dirac composite fermions

Antti Laitinen, Manohar Kumar, Pertti J. Hakonen

摘要:

分数量子霍尔系统中的复合费米子被认为在半充满$ν=1/2$时形成弱相互作用粒子的费米海。最近,有人提出(D。T. Son,Phys.Rev.X5,031027(2015)),这些复合费米子是狄拉克粒子。在我们的工作中,我们实验证明,在单层石墨烯中发现的复合费米子是狄拉克粒子在半填充。我们的实验已经解决了在$ν=1/2$附近的高迁移率,悬浮的石墨烯Corbino盘中的H2O态。我们发现强烈的温度依赖性的电导率$σ$远离半填充,这是符合预期的电子-电子相互作用诱导的间隙在CH 3OH状态。然而,在半填充,电导率的温度依赖性$σ(T)$变得相当弱,正如预期的费米海的复合费米子,我们发现只有对数依赖$σ$上$T$。这种量子修正的符号与复合费米子的弱反定域相吻合,这揭示了石墨烯中复合费米子的相对论狄拉克性质。

英文摘要:

Composite fermions in fractional quantum Hall (FQH) systems are believed to form a Fermi sea of weakly interacting particles at half filling $ν=1/2$. Recently, it was proposed (D. T. Son, Phys. Rev. X 5, 031027 (2015)) that these composite fermions are Dirac particles. In our work, we demonstrate experimentally that composite fermions found in monolayer graphene are Dirac particles at half filling. Our experiments have addressed FQH states in high-mobility, suspended graphene Corbino disks in the vicinity of $ν=1/2$. We find strong temperature dependence of conductivity $σ$ away from half filling, which is consistent with the expected electron-electron interaction induced gaps in the FQH state. At half filling, however, the temperature dependence of conductivity $σ(T)$ becomes quite weak as expected for a Fermi sea of composite fermions and we find only logarithmic dependence of $σ$ on $T$. The sign of this quantum correction coincides with weak antilocalization of composite fermions, which reveals the relativistic Dirac nature of composite fermions in graphene.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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