论文标题
创纪录的GAAS二维孔系统
Record-quality GaAs two-dimensional hole systems
论文作者
论文摘要
复杂的带结构，大型旋转轨道诱导的带状分裂以及在GAAS量子井中托管的二维（2D）孔系统的重质量，使它们使它们具有丰富的平台，以研究多体物理和弹道传输现象。 Here we report ultra-high-quality (001) GaAs 2D hole systems, fabricated using molecular beam epitaxy and modulation doping, with mobility values as high as $5.8\times10^6$ cm$^2$/Vs at a hole density of $p=1.3\times10^{11}$ /cm$^2$, implying a mean-free path of $\simeq27$ $μ$ m。在该样品的低温磁磁性轨迹中，我们观察到高阶分数量子厅一直列出到Landau级别，填充$ν= 12/25 $接近$ν= 1/2 $。此外，我们看到在$ν= 1/5 $的最低最低限度中，在较低的孔密度为$ p = 4.0 \ times10^{10} $/cm $^2 $的样品的磁性中，我们衡量的是$ 3.6 \ times10^6 $ cm $^2 $^2 $^2 $/vs。通过减少GAAS通道和藻类屏障材料中的残留杂质，以及样品结构设计的优化，可以实现样品质量的这些改善。
The complex band structure, large spin-orbit induced band splitting, and heavy effective mass of two-dimensional (2D) hole systems hosted in GaAs quantum wells render them rich platforms to study many-body physics and ballistic transport phenomena. Here we report ultra-high-quality (001) GaAs 2D hole systems, fabricated using molecular beam epitaxy and modulation doping, with mobility values as high as $5.8\times10^6$ cm$^2$/Vs at a hole density of $p=1.3\times10^{11}$ /cm$^2$, implying a mean-free path of $\simeq27$ $μ$m. In the low-temperature magnetoresistance trace of this sample, we observe high-order fractional quantum Hall states up to the Landau level filling $ν=12/25$ near $ν=1/2$. Furthermore, we see a deep minimum develop at $ν=1/5$ in the magnetoresistance of a sample with a much lower hole density of $p=4.0\times10^{10}$ /cm$^2$ where we measure a mobility of $3.6\times10^6$ cm$^2$/Vs. These improvements in sample quality were achieved by reduction of residual impurities both in the GaAs channel and the AlGaAs barrier material, as well as optimization in design of the sample structure.
