Theory of Spin Transport Induced by Ferromagnetic Proximity On a Two-Dimensional Electron Gas

TL;DR

This paper develops a theoretical framework for understanding how ferromagnetic proximity effects induce spin transport in a two-dimensional electron gas, with implications for spintronic device design.

Contribution

It introduces a new theory describing spin-dependent energy, lifetime, and transport in 2DEGs influenced by ferromagnetic proximity, including current leakage and device applications.

Findings

Spin-splitting in in-plane current due to ferromagnetic proximity.

Competition between drift and diffusion in current leakage.

Potential for spintronic devices using planar ferromagnetic gates.

Abstract

A theory of the proximity effects of the exchange splitting in a ferromagnetic metal on a two dimensional electron gas (2DEG) in a semiconductor is presented. The resulting spin-dependent energy and lifetime in the 2DEG create a marked spin-splitting in the driven in-plane current. The theory of the planar transport allows for current leakage into the ferromagnetic layer through the interface, which leads to a competition between drift and diffusion. The spin-dependent in-plane conductivity of the 2DEG may be exploited to provide a new paradigm for spintronics devices based on planar devices in a field-effect transistor configuration. An illustrative example is provided through the transport theory of a proposed spin-valve which consists of a field-effect transistor configuration with two ferromagnetic gates. Results are provided for two experimentally accessible systems: the silicon inversion layer and the naturally-formed InAs accumulation layer.