Yang Fangyuan, Bai Ruiheng, Zibrov Alexander A, Joy Sandeep, Taniguchi Takashi, Watanabe Kenji, Skinner Brian, Goerbig Mark O, Young Andrea F
Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106, USA.
Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.
Phys Rev Lett. 2023 Dec 1;131(22):226501. doi: 10.1103/PhysRevLett.131.226501.
The phase diagram of an interacting two-dimensional electron system in a high magnetic field is enriched by the varying form of the effective Coulomb interaction, which depends strongly on the Landau level index. While the fractional quantum Hall states that dominate in the lower-energy Landau levels have been explored experimentally in a variety of two-dimensional systems, much less work has been done to explore electron solids owing to their subtle transport signatures and extreme sensitivity to disorder. Here, we use chemical potential measurements to map the phase diagram of electron solid states in N=2, N=3, and N=4 Landau levels in monolayer graphene. Direct comparison between our data and theoretical calculations reveals a cascade of density-tuned phase transitions between electron bubble phases up to two, three, or four electrons per bubble in the N=2, 3, and 4 Landau levels, respectively. Finite-temperature measurements are consistent with melting of the solids for T≈1 K.
在高磁场中，相互作用的二维电子系统的相图因有效库仑相互作用形式的变化而丰富，有效库仑相互作用强烈依赖于朗道能级指数。虽然在各种二维系统中已通过实验探索了在低能朗道能级中占主导的分数量子霍尔态，但由于电子固体的输运特征微妙且对无序极其敏感，对其进行探索的工作要少得多。在此，我们利用化学势测量来绘制单层石墨烯中N = 2、N = 3和N = 4朗道能级的电子固体态相图。我们的数据与理论计算之间的直接比较揭示了在N = 2、3和4朗道能级中，分别在每个气泡有多达两个、三个或四个电子的电子气泡相之间存在一系列密度调谐的相变。有限温度测量结果与T≈1 K时固体的熔化情况一致。
