Resonant charge and spin transport in a t-stub coupled to a superconductor

TL;DR

This paper investigates how a t-stub coupled to a superconductor affects charge and spin transport, revealing unique resonant behavior with a single transmission resonance at T=1/4 where charge transport stops but spin transport is perfect.

Contribution

It demonstrates that the proximity effect alters the standard resonance pattern, resulting in a single resonance at T=1/4 with distinct charge and spin transport properties.

Findings

Charge transport vanishes at T=1/4 resonance.

Spin transport remains perfect at T=1/4 resonance.

Standard resonances and anti-resonances are suppressed by the superconductor.

Abstract

We study transport through a single channel t-stub geometry strongly coupled to a superconducting reservoir. In contrast to the standard stub geometry which has both transmission resonances and anti-resonances in the coherent limit, we find that due to the proximity effect, this geometry shows neither a T=1 resonance (T is the transmission probability for electrons incident on the t-stub) nor a T=0 anti-resonance as we vary the energy of the incident electron. Instead, we find that there is only one resonant value at T=1/4, where charge transport vanishes while the spin transport is perfect.