Spin-injection spectra of CoFe/GaAs contacts: dependence on Fe concentration, interface and annealing conditions

TL;DR

This study investigates how the spin-injection spectra from CoFe and Fe contacts into GaAs are affected by interface composition and annealing, revealing key spectral features and their dependence on interface conditions.

Contribution

It provides new experimental insights into how Fe concentration, interface chemistry, and annealing influence spin-injection spectra in CoFe/GaAs contacts.

Findings

Presence of minority-spin peak at forward bias

Majority-spin peak observed at reverse bias

Spin-injection efficiency correlates with interface Ga-to-As ratio

Abstract

Spin injection from Co70Fe30 and Fe contacts into bulk GaAs(001) epilayers is studied experimentally. Using nonlocal measurements, the spin polarization of the differential conductance is determined as a function of the bias voltage applied across the injection interface. The spectra reveal an interface-related minority-spin peak at forward bias and a majority-spin peak at reverse bias, and are very similar, but shifted in energy, for Co70Fe30 and for Fe contacts. An increase of the spin-injection efficiency and a shift of the spectrum correlate with the Ga-to-As ratio at the interface between CoFe and GaAs.