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

Determining the (bare) electron mass m0 in crystals is often hindered by many-body effects since Fermi-liquid physics renormalizes 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 m0. 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 m0=(0.0525±0.0015)me in this material, where me is the free-electron mass. By varying the density in the wires, we change the interaction parameter rs in the range from ∼1-4 and show that m0 remains constant. The determined value of m0 is ∼22% lighter than observed in GaAs in geometries of higher dimensionality D (D>1), consistent with the quasiparticle picture of a Fermi liquid that makes electrons heavier in the presence of interactions.