Transference of Transport Anisotropy to Composite Fermions

TL;DR

This paper investigates whether the anisotropic properties of electrons, such as effective mass and Fermi surface shape, are preserved when electrons form composite fermions in high magnetic fields, showing that CFs also exhibit anisotropic transport.

Contribution

It demonstrates experimentally that composite fermions inherit the electron effective mass and Fermi surface anisotropy, revealing a fundamental link between electron and CF anisotropic properties.

Findings

CFs exhibit anisotropic transport similar to electrons

Anisotropy of CF effective mass and Fermi surface confirmed

Supports the idea that CFs retain electron anisotropic characteristics

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 (FS) survive composite fermionization? We measure the resistance of CFs in AlAs quantum wells where electrons occupy an elliptical FS 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 FS.