Complete spin polarization of degenerate electrons in semiconductors near ferromagnetic contacts

TL;DR

This paper demonstrates that complete spin polarization of electrons can be achieved in nonmagnetic degenerate semiconductors near ferromagnetic contacts, even with moderate contact selectivity, by analyzing electron diffusion and current relations.

Contribution

It introduces a general equation linking spin polarization of current and electron density, revealing conditions for full spin polarization near the $n^{+}$-$n$ interface.

Findings

Achieves 100% spin polarization in degenerate semiconductors near ferromagnetic contacts.

Derives a relation between spin polarization of current and electron density.

Identifies conditions where diffusion coefficient approaches zero, enabling full polarization.

Abstract

We show that spin polarization of electron density in nonmagnetic degenerate semiconductors can achieve 100%. This effect is realized in ferromagnet-semiconductor $FM-n^{+}$-$n$ junctions even at moderate spin selectivity of the $FM-n^{+}$ contact when the electrons are extracted from the heavily doped $n^{+}-$semiconductor into the ferromagnet. We derived a general equation relating spin polarization of the current to that of the electron density in nonmagnetic semiconductors. We found that the effect of the complete spin polarization is achieved near $n^{+}$-$n$ interface when an effective diffusion coefficient goes to zero in this region while the diffusion current remains finite.