Shubnikov-de Haas oscillations in GaAs quantum wells in tilted magnetic fields

TL;DR

This study investigates Shubnikov-de Haas oscillations in high-mobility GaAs quantum wells under tilted magnetic fields, revealing unique spin and cyclotron splitting behaviors and level crossings explained by in-plane field effects.

Contribution

It demonstrates the continuous equality of spin and cyclotron splittings at specific angles and explains oscillation patterns via in-plane field-induced mass increase.

Findings

Spin and cyclotron splittings become equal over a range of angles.

Beating patterns in oscillations indicate level crossings at specific angles.

In-plane magnetic fields increase carrier mass, affecting level crossings.

Abstract

We report on quantum magneto-oscillations in an ultra-high mobility GaAs/AlGaAs quantum well at very high tilt angles. Unlike previous studies, we find that the spin and cyclotron splittings become equal over a continuous range of angles, but only near certain, angle-dependent filling factors. At high enough tilt angles, Shubnikov-de Haas oscillations reveal a prominent beating pattern, indicative of consecutive level crossings, all occurring at the same angle. We explain these unusual observations by an in-plane field-induced increase of the carrier mass, which leads to accelerated, filling factor-driven crossings of spin sublevels in tilted magnetic fields.