Positive Quantum Magnetoresistance in Tilted Magnetic Field

TL;DR

This study investigates how tilted magnetic fields affect quantum positive magnetoresistance in high-mobility 2D electrons in GaAs wells, revealing complex spin interactions and spectrum transformations.

Contribution

It provides new insights into the angular dependence of QPMR and the role of spin-orbit interactions in electron spectrum modifications under tilted magnetic fields.

Findings

QPMR observed in perpendicular magnetic fields.

In-plane magnetic field reduces QPMR significantly.

No spectrum quantization detected beyond certain Zeeman energy.

Abstract

Transport properties of highly mobile 2D electrons are studied in symmetric GaAs quantum wells placed in titled magnetic fields. Quantum positive magnetoresistance (QPMR) is observed in magnetic fields perpendicular to the 2D layer. Application of in-plane magnetic field produces a dramatic decrease of the QPMR. This decrease correlates strongly with the reduction of the amplitude of Shubnikov de Haas resistance oscillations due to modification of the electron spectrum via enhanced Zeeman splitting. Surprisingly no quantization of the spectrum is detected when the Zeeman energy exceeds the half of the cyclotron energy suggesting an abrupt transformation of the electron dynamics. Observed angular evolution of QPMR implies strong mixing between spin subbands. Theoretical estimations indicate that in the presence of spin-orbital interaction the elastic impurity scattering provides significant contribution to the spin mixing in GaAs quantum wells at high filling factors.