New spin injection scheme based on spin gapless semiconductors: A first-principles study

TL;DR

This study proposes using spin gapless semiconductors as spin injectors to overcome conductivity mismatch issues, demonstrating through first-principles calculations that this approach maintains high spin polarization and enhances spin injection efficiency.

Contribution

The paper introduces a novel spin injection scheme replacing metallic injectors with spin gapless semiconductors, reducing conductivity mismatch and improving efficiency based on first-principles analysis.

Findings

High spin polarization maintained at interfaces

Long spin diffusion length in Mn2CoAl/GaAs system

Pronounced dip in density-of-states indicating fast carrier transport

Abstract

Spin injection efficiency based on conventional and/or half-metallic ferromagnet/semiconductor is greatly limited by the Schmidt obstacle due to conductivity mismatch, here we proposed that by replacing the metallic injectors with spin gapless semiconductors can significantly reduce the conductive mismatch to enhance spin injection efficiency. By performing first principles calculations based on superlattice structure, we have studied the representative system of Mn2CoAl/semiconductor spin injector scheme. The results showed that a high spin polarization was maintained at the interface in systems of Mn2CoAl/Fe2VAl constructed with (100) interface and Mn2CoAl/GaAs with (110) interface, and the latter is expected to possess long spin diffusion length. Inherited from the spin gapless feature of Mn2CoAl, a pronounced dip was observed around the Fermi level in the majority-spin density-of-states in both systems, suggesting fast transport of the low-density carriers.