Theory of Josephson transport through spintronics nano-structure

TL;DR

This paper develops a theoretical framework for Josephson transport through ferromagnetic insulators, revealing conditions for pi-junction formation and atomic-scale 0-pi transitions, with implications for quantum computing.

Contribution

It explicitly incorporates band structure effects in Josephson transport through ferromagnetic insulators, highlighting new mechanisms for pi-junction formation.

Findings

Pi-junction formation in fully polarized ferromagnetic insulators.

Atomic-scale 0-pi transitions induced by FI thickness.

Orbital hybridization in Eu chalcogenides leads to pi-junction behavior.

Abstract

We study the Josephson transport through ferromagnetic insulators (FIs) by taking into account its band structure explicitly. In the case of the fully polarized FIs (FPFIs), we found the formation of a pi-junction and an atomic-scale 0-pi transition induced by increasing the FI thickness. More remarkably, in the Josephson junction through spin-filter materials such as Eu chalcogenides, the orbital hybridization between the conduction d and the localized f electron gives rise to the pi-junction behavior. Such FI-based pi-junctions can be used to implement highly-coherent solid-state quantum bits.