Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Phys Rev Lett. 2010 Jul 30;105(5):056804. doi: 10.1103/PhysRevLett.105.056804.
We investigate dynamic nuclear polarization in quantum point contacts (QPCs) in the integer and fractional quantum Hall regimes. Following the application of a dc bias, fractional plateaus in the QPC shift symmetrically about half filling of the lowest Landau level, ν=1/2, suggesting an interpretation in terms of composite fermions. Polarizing and detecting at different filling factors indicates that Zeeman energy is reduced by the induced nuclear polarization. Mapping effects from integer to fractional regimes extends the composite fermion picture to include hyperfine coupling.
我们研究了整数和分数量子霍尔区中量子点接触（QPC）中的动态核极化。在施加直流偏压后，QPC 中的分数平台关于最低朗道能级的半填充（ν=1/2）对称地移动，这表明可以用复合费米子来解释。在不同填充因子下进行极化和检测表明，诱导的核极化降低了塞曼能。从整数区到分数量子霍尔区的映射效应将复合费米子图像扩展到包括超精细耦合。
