The Effect of Ramsauer Type Transmission Resonances on the Conductance Modulation of Spin Interferometers

TL;DR

This paper investigates how Ramsauer type transmission resonances, caused by contact reflections, dominate conductance modulation in semiconductor spin interferometers over the Rashba effect, highlighting the importance of contact engineering.

Contribution

It reveals that conductance modulation in spin interferometers is primarily due to Ramsauer resonances, not the Rashba effect, emphasizing the need to control contact reflections.

Findings

Ramsauer resonances significantly influence conductance modulation.

Reflections at contacts overshadow Rashba effect contributions.

Proper contact design is crucial for accurate spin interference measurements.

Abstract

We use a mean field approach to study the conductance modulation of gate controlled semiconductor spin interferometers based on the Rashba spin-orbit coupling effect. The conductance modulation is found to be mostly due to Ramsauer type transmission resonances rather than the Rashba effect in typical structures. This is because of significant reflections at the interferometer's contacts due to large potential barriers and effective mass mismatch between the contact material and the semiconductor. Thus, unless particular care is taken to eliminate these reflections, any observed conductance modulation of spin interferometers may have its origin in the Ramsauer resonances (which is unrelated to spin) rather than the Rashba effect.