Bipolar spintronics: From spin injection to spin-controlled logic

TL;DR

This paper explores the potential of semiconductor-based bipolar spintronic devices that leverage nonlinear current-voltage characteristics for spin-controlled logic, expanding beyond traditional metallic spintronics applications.

Contribution

It introduces a theoretical framework for bipolar spin-polarized transport in semiconductors and discusses novel effects arising from spin-charge coupling in such structures.

Findings

Formulated a theoretical model for bipolar spin transport.

Identified new effects from spin and magnetization interplay.

Proposed structures for spin-based logic applications.

Abstract

An impressive success of spintronic applications has been typically realized in metal-based structures which utilize magnetoresistive effects for substantial improvements in the performance of computer hard drives and magnetic random access memories. Correspondingly, the theoretical understanding of spin-polarized transport is usually limited to a metallic regime in a linear response, which, while providing a good description for data storage and magnetic memory devices, is not sufficient for signal processing and digital logic. In contrast, much less is known about possible applications of semiconductor-based spintronics and spin-polarized transport in related structures which could utilize strong intrinsic nonlinearities in current-voltage characteristics to implement spin-based logic. Here we discuss the challenges for realizing a particular class of structures in semiconductor spintronics: our proposal for bipolar spintronic devices in which carriers of both polarities (electrons and holes) contribute to spin-charge coupling. We formulate the theoretical framework for bipolar spin-polarized transport, and describe several novel effects in two- and three-terminal structures which arise from the interplay between nonequilibrium spin and equilibrium magnetization.