Probing semiclassical magneto-oscillations in the low-field quantum Hall effect

TL;DR

This study investigates low-field quantum Hall effects in a 2D electron system, revealing semiclassical magneto-oscillations that persist despite quantum localization, and discusses the transition from semiclassical to quantum diffusion.

Contribution

It demonstrates the survival of semiclassical oscillations and formulas in low-field quantum Hall regimes, highlighting the role of electron states away from Landau-band tails.

Findings

Magneto-oscillations follow the semiclassical Shubnikov-de Haas formula.

Lifshitz-Kosevich formula remains valid at large oscillation amplitudes.

Difference between mobility and cyclotron gaps suggests involvement of states away from Landau-band tails.

Abstract

The low-field quantum Hall effect is investigated on a two-dimensional electron system in an AlGaAs/GaAs heterostructure. Magneto-oscillations following the semiclassical Shubnikov-de Haas formula are observed even when the emergence of the mobility gap shows the importance of quantum localization effects. Moreover, the Lifshitz-Kosevich formula can survive as the oscillating amplitude becomes large enough for the deviation to the Dingle factor. The crossover from the semiclassical transport to the description of quantum diffusion is discussed. From our study, the difference between the mobility and cyclotron gaps indicates that some electron states away from the Landau-band tails can be responsible for the semiclassical behaviors under low-field Landau quantization.