Decoupling of the many-body effects from the electron mass in GaAs by means of reduced dimensionality

TL;DR

This study isolates the bare electron mass in GaAs by using one-dimensional quantum wires to suppress many-body effects, revealing a lighter intrinsic mass than in higher-dimensional systems.

Contribution

It demonstrates a method to decouple many-body interaction effects from the electron mass in GaAs using 1D quantum wires and magnetotunnelling spectroscopy.

Findings

Measured the bare electron mass as 0.0525 m_e in GaAs.

Found the bare mass remains constant across different densities.

Observed the bare mass is 22% lighter than in higher-dimensional geometries.

Abstract

Determining the (bare) electron mass $m_0$ in crystals is often hindered by many-body effects since Fermi-liquid physics renormalises the band mass, making the observed effective mass $m^*$ depend on density. Here, we use a one-dimensional (1D) geometry to amplify the effect of interactions, forcing the electrons to form a nonlinear Luttinger liquid with separate holon and spinon bands, therefore separating the interaction effects from $m_0$. Measuring the spectral function of gated quantum wires formed in GaAs by means of magnetotunnelling spectroscopy and interpreting them using the 1D Fermi-Hubbard model, we obtain $m_0=(0.0525\pm0.0015)m_\textrm{e}$ in this material, where $m_\textrm{e}$ is the free-electron mass. By varying the density in the wires, we change the interaction parameter $r_\textrm{s}$ in the range from $\sim$1-4 and show that $m_0$ remains constant. The determined value of $m_0$ is $\sim 22$% lighter than observed in GaAs in geometries of higher dimensionality $D$ ($D>1$), consistent with the quasi-particle picture of a Fermi liquid that makes electrons heavier in the presence of interactions.