Spin-filter effect of the europium chalcogenides: An exactly solved many-body model

TL;DR

This paper presents an exactly solvable many-body model for spin filtering in europium chalcogenides, explaining high electron spin polarization through s-f interactions, electric fields, and geometry.

Contribution

It introduces an analytical model capturing key experimental features of spin filtering, including spin-flip probabilities and polarization dependencies.

Findings

Electron spin polarization reaches about 90%.

Spin polarization depends on electron velocity and s-f coupling strength.

Model aligns well with experimental observations.

Abstract

A model Hamiltonian is introduced which considers the main features of the experimental spin filter situation as s-f interaction, planar geometry and the strong external electric field. The proposed many-body model can be solved analytically and exactly using Green functions. The spin polarization of the field-emitted electrons is expressed in terms of spin-flip probabilities, which on their part are put down to the exactly known dynamic quantities of the system. The calculated electron spin polarization shows remarkable dependencies on the electron velocity perpendicular to the emitting plane and the strength of s-f coupling. Experimentally observed polarization values of about 90% are well understood within the framework of the proposed model.