Experimental Studies of Low-field Landau Quantization in Two-dimensional Electron Systems in GaAs/AlGaAs Heterostructures

TL;DR

This study investigates low-field Landau quantization in GaAs/AlGaAs 2D electron systems, revealing persistent magneto-oscillations at low temperatures and highlighting the role of positive magneto-resistance in extending the applicability of the SdH formula.

Contribution

It provides experimental evidence of Landau quantization effects at low magnetic fields and discusses the influence of disorder and positive magneto-resistance on quantum oscillations.

Findings

Magneto-oscillations follow the SdH formula even at large amplitudes.

Positive magneto-resistance extends the validity of the SdH formula.

Quantum oscillations are observed at low magnetic fields and temperatures.

Abstract

By applying a magnetic field perpendicular to GaAs/AlGaAs two-dimensional electron systems, we study the low-field Landau quantization when the thermal damping is reduced with decreasing the temperature. Magneto-oscillations following Shubnikov-de Haas (SdH) formula are observed even when their amplitudes are so large that the deviation to such a formula is expected. Our experimental results show the importance of the positive magneto-resistance to the extension of SdH formula under the damping induced by the disorder.