Sawtoothlike de Haas–van Alphen oscillations of a two-dimensional electron system
Sawtoothlike de Haas–van Alphen oscillations of a two-dimensional electron system
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DOI：
10.1103/physrevb.65.245315
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发表时间：
2002-06
影响因子：
3.7
通讯作者：
M. P. Schwarz;M. Wilde;S. Groth;D. Grundler;C. Heyn;D. Heitmann
中科院分区：
文献类型：
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作者：
M. P. Schwarz;M. Wilde;S. Groth;D. Grundler;C. Heyn;D. Heitmann
我们提出了整数量子霍尔效应体系中二维电子系统（2DES）低温磁化的研究。 2DES 是在调制掺杂的 AlGaAs/GaAs 异质结中形成的。使用分子束外延，它已被集成到高灵敏度的微机械悬臂磁力计中。我们观察到即使填充因子达到 ν=40 时的德哈斯-范阿尔芬振荡，当 ν< 20 时，它几乎是完美的锯齿状。奇数填充因子 ν=3、5、7 和 9 处的振荡是由于朗道能级的自旋分裂造成的。为了对我们的数据进行定量分析，我们根据模型态密度 (DOS) 计算了磁化强度。我们通过具有能量无关背景的窄高斯展宽朗道能级来描述 DOS。特别是，我们发现背景 DOS 随 ν 线性增加。使用边缘通道的概念可以定性地解释这种行为。根据我们的数据，我们评估了能级展宽，以及在奇数填充因子下，交换能量对朗道能级自旋分裂的贡献。
We present studies on the low-temperature magnetization of a two-dimensional electron system (2DES) in the integer quantum Hall-effect regime. The 2DES was formed in a modulation-doped AlGaAs/GaAs heterojunction. Using molecular-beam epitaxy it has been integrated into a highly sensitive micromechanical cantilever magnetometer. We observe de Haas–van Alphen oscillations at even filling factors up to ν=40 which for ν< 20 are almost perfectly sawtoothlike. Oscillations at odd filling factors ν=3,5,7, and 9 are due to the spin splitting of Landau levels. For a quantitative analysis of our data, calculations of the magnetization based on a model density of states (DOS) have been performed. We describe the DOS by narrow Gaussian broadened Landau levels with an energy-independent background. In particular we find that this background DOS increases linearly with ν. This behavior is qualitatively explained using the concept of edge channels. From our data we evaluate the level broadening and, at odd filling factors, the exchange-energy contribution to the spin splitting of Landau levels.