We report experimental observation of the reentrant integer quantum Hall effect in graphene, appearing in the

$N=2$

Landau level. Similar to high-mobility

$\mathrm{GaAs}/\mathrm{AlGaAs}$

heterostructures, the effect is due to a competition between incompressible fractional quantum Hall states, and electron solid phases. The tunability of graphene allows us to measure the

$B\text{−}T$

phase diagram of the electron solid phase. The hierarchy of reentrant states suggests spin and valley degrees of freedom play a role in determining the ground state energy. We find that the melting temperature scales with magnetic field, and construct a phase diagram of the electron liquid-solid transition.

中文翻译：

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石墨烯中竞争的分数量子霍尔和电子固相

我们报告了石墨烯中可重入整数量子霍尔效应的实验观察，该现象出现在石墨烯中。

$ñ=\mathrm{2个}$

兰道级。类似于高机动性

$\mathrm{砷化镓}/\mathrm{铝镓砷}$

异质结构，其影响是由于不可压缩的分数量子霍尔态与电子固相之间的竞争。石墨烯的可调性使我们能够测量

$乙\text{-}Ť$

电子固相的相图。折返态的等级表明，自旋和谷自由度在确定基态能量中起作用。我们发现熔化温度与磁场成比例，并构造了电子液-固转变的相图。