Semiconductor Spintronics

TL;DR

This paper reviews the fundamental concepts, theoretical models, and experimental progress in semiconductor spintronics, emphasizing spin transport, injection, spin-orbit coupling, and device proposals like magnetic tunnel structures and bipolar transistors.

Contribution

It provides a comprehensive tutorial-style overview of key concepts, effective Hamiltonians, and recent device proposals in semiconductor spintronics, integrating theory and experimental insights.

Findings

Derivation of effective spin-orbit Hamiltonians for various materials

Discussion of theoretical device concepts awaiting experimental realization

Analysis of spin-dependent tunneling and spin relaxation mechanisms

Abstract

Spintronics refers commonly to phenomena in which the spin of electrons in a solid state environment plays the determining role. In a more narrow sense spintronics is an emerging research field of electronics: spintronics devices are based on a spin control of electronics, or on an electrical and optical control of spin or magnetism. This review presents selected themes of semiconductor spintronics, introducing important concepts in spin transport, spin injection, Silsbee-Johnson spin-charge coupling, and spindependent tunneling, as well as spin relaxation and spin dynamics. The most fundamental spin-dependent nteraction in nonmagnetic semiconductors is spin-orbit coupling. Depending on the crystal symmetries of the material, as well as on the structural properties of semiconductor based heterostructures, the spin-orbit coupling takes on different functional forms, giving a nice playground of effective spin-orbit Hamiltonians. The effective Hamiltonians for the most relevant classes of materials and heterostructures are derived here from realistic electronic band structure descriptions. Most semiconductor device systems are still theoretical concepts, waiting for experimental demonstrations. A review of selected proposed, and a few demonstrated devices is presented, with detailed description of two important classes: magnetic resonant tunnel structures and bipolar magnetic diodes and transistors. In most cases the presentation is of tutorial style, introducing the essential theoretical formalism at an accessible level, with case-study-like illustrations of actual experimental results, as well as with brief reviews of relevant recent achievements in the field.