Spin-filter tunnel junction with matched Fermi surfaces

TL;DR

This paper demonstrates that matching Fermi-surface shapes in spin-filter tunnel junctions significantly enhances spin injection efficiency by reducing spin scattering, highlighting the importance of electronic structure alignment in spintronic device performance.

Contribution

It introduces the concept of Fermi-surface matching as a key factor for improving spin injection efficiency in ferromagnetic insulator tunnel junctions.

Findings

Fermi-surface matching increases spin injection efficiency.

Spin scattering is reduced with matched Fermi surfaces.

Structural and electronic matching are both crucial for device performance.

Abstract

Efficient injection of spin-polarized current into a semiconductor is a basic prerequisite for building semiconductor-based spintronic devices. Here, we use inelastic electron tunneling spectroscopy to show that the efficiency of spin-filter-type spin injectors is limited by spin scattering of the tunneling electrons. By matching the Fermi-surface shapes of the current injection source and target electrode material, spin injection efficiency can be significantly increased in epitaxial ferromagnetic insulator tunnel junctions. Our results demonstrate that not only structural but also Fermi-surface matching is important to suppress scattering processes in spintronic devices.