Parallel magnetic field induced magnetoresistance peculiarities of the double quantum well filled with electrons or holes

TL;DR

This study investigates how parallel magnetic fields affect magnetoresistance in double quantum wells with electrons or holes, revealing unique features linked to spin-splitting and subband structure at high magnetic fields.

Contribution

It uncovers magnetoresistance peculiarities caused by tunnel gap edges and subband shapes in double quantum wells, including effects of spin-splitting in InGaAs/GaAs structures.

Findings

Magnetoresistance features appear at high fields (~30 T) due to spin-splitting effects.

Local MR peculiarities in hole gases are linked to subband shape, not tunnel gap.

Spin-splitting effects are significant in InGaAs/GaAs heterostructures, unlike in GaAs/AlGaAs.

Abstract

In In_xGa_{1-x}As/n-GaAs double quantum wells (DQWs) containing an electron gas, the magnetoresistance (MR) peculiarities under parallel magnetic fields caused by the passing of the tunnel gap edges through the Fermi level are revealed. Peculiarities positioned in high fields (~30 T) can only be explained if the spin-splitting of the In_xGa_{1-x}As conduction band is considered, that was neglected in the GaAs/AlGaAs heterostructures, for which solely the effects of this nature have been observed so far. In Ge/p-Ge_{1-x}Si_x DQWs containing a hole gas, local MR peculiarities under parallel fields are discovered as well. But the tunnel gap in these DQWs is too narrow to be responsible for these observations. We suppose, they are due to a complicated shape of the hole confinement subbands.