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Transference of transport anisotropy to composite fermions

Nature Physics volume 6, pages 621–624 (2010)Cite this article

Abstract

When interacting two-dimensional electrons are placed in a large perpendicular magnetic field, to minimize their energy, they capture an even number of flux quanta and create new particles called composite fermions (CFs). These complex electron-flux-bound states offer an elegant explanation for the fractional quantum Hall effect. Furthermore, thanks to the flux attachment, the effective field vanishes at a half-filled Landau level and CFs exhibit Fermi-liquid-like properties, similar to their zero-field electron counterparts. However, being solely influenced by interactions, CFs should possess no memory whatever of the electron parameters. Here we address a fundamental question. Does an anisotropy of the electron effective mass and Fermi surface survive composite fermionization? We measure the resistance of CFs in AlAs quantum wells where electrons occupy an elliptical Fermi surface with large eccentricity and anisotropic effective mass. Similar to their electron counterparts, CFs also exhibit anisotropic transport, suggesting an anisotropy of CF effective mass and Fermi surface.

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Figure 1: Schematic diagrams of 2D electrons and CFs in real and reciprocal spaces.
Figure 2: The piezoresistance data, valley occupations and LL diagrams of electrons and CFs at ν=1/2.
Figure 3: The piezoresistance data of electrons at B=0 and CFs at ν=3/2.
Figure 4: The piezoresistance of CFs at ν=3/2 at high density.
Figure 5: The piezoresistance of CFs at ν=3/2 at density n=2.10×1011 cm−2.

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Acknowledgements

We thank the NSF and DOE for support, and J. K. Jain and B. I. Halperin for discussions.

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Authors and Affiliations

  1. Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA

    T. Gokmen, Medini Padmanabhan & M. Shayegan

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  1. T. Gokmen
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  2. Medini Padmanabhan
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  3. M. Shayegan
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Contributions

T.G. and M.P. carried out the experiments. All authors discussed the results and analysed the data. T.G. and M.S. wrote the manuscript.

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Correspondence to T. Gokmen.

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The authors declare no competing financial interests.

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Gokmen, T., Padmanabhan, M. & Shayegan, M. Transference of transport anisotropy to composite fermions. Nature Phys 6, 621–624 (2010). https://doi.org/10.1038/nphys1684

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