Influence of interface structure on electronic properties and Schottky barriers in Fe/GaAs magnetic junctions

TL;DR

This study uses first-principles calculations to explore how different interface structures in Fe/GaAs magnetic junctions affect electronic properties, Schottky barriers, and spin polarization, with implications for spin-injection devices.

Contribution

It provides detailed insights into how interface termination and intermixing influence electronic and magnetic properties in Fe/GaAs junctions, highlighting the role of interface states.

Findings

Schottky barrier heights are highly sensitive to interface abruptness.

As-terminated interfaces favor abrupt Fe/GaAs contacts.

Metal interface states induce spin polarization in the semiconductor.

Abstract

The electronic and magnetic properties of Fe/GaAs(001) magnetic junctions are investigated using first-principles density-functional calculations. Abrupt and intermixed interfaces are considered, and the dependence of charge transfer, magnetization profiles, Schottky barrier heights, and spin polarization of densities of states on interface structure is studied. With As-termination, an abrupt interface with Fe is favored, while Ga-terminated GaAs favors the formation of an intermixed layer with Fe. The Schottky barrier heights are particularly sensitive to the abruptness of the interface. A significant density of states in the semiconducting gap arises from metal interface states. These spin-dependent interface states lead to a significant minority spin polarization of the density of states at the Fermi level that persists well into the semiconductor, providing a channel for the tunneling of minority spins through the Schottky barrier. These interface-induced gap states and their dependence on atomic structure at the interface are discussed in connection with potential spin-injection applications.