Low field magnetotransport in strained Si/SiGe cavities

TL;DR

This study investigates low field magnetotransport in strained Si/SiGe cavities, revealing ballistic effects, a zero-field magnetoresistance peak, and electron magnetic focusing, with deviations from weak localization theory.

Contribution

It demonstrates how geometrical modeling explains oscillatory magnetoresistance and highlights deviations from existing ballistic localization theories in strained Si/SiGe structures.

Findings

Observation of zero-field magnetoresistance peak

Detection of oscillatory structure at low magnetic fields

Deviations from weak localization predictions

Abstract

Low field magnetotransport revealing signatures of ballistic transport effects in strained Si/SiGe cavities is investigated. We fabricated strained Si/SiGe cavities by confining a high mobility Si/SiGe 2DEG in a bended nanowire geometry defined by electron-beam lithography and reactive ion etching. The main features observed in the low temperature magnetoresistance curves are the presence of a zero-field magnetoresistance peak and of an oscillatory structure at low fields. By adopting a simple geometrical model we explain the oscillatory structure in terms of electron magnetic focusing. A detailed examination of the zero-field peak lineshape clearly shows deviations from the predictions of ballistic weak localization theory.