Spin-polarized Quantum Transport in Mesoscopic Conductors: Computational Concepts and Physical Phenomena

TL;DR

This paper reviews the quantum transport phenomena in mesoscopic conductors, emphasizing spin effects, and discusses computational algorithms for analyzing spin-dependent transport in these systems.

Contribution

It introduces and reviews numerical algorithms, including matrix-reordering techniques within Green function approaches, for studying spin-dependent mesoscopic transport.

Findings

Quantum interference affects conductance in mesoscopic systems.

Spin phenomena can be controlled and engineered in mesoscopic conductors.

Efficient algorithms enable detailed analysis of spin-dependent transport.

Abstract

Mesoscopic conductors are electronic systems of sizes in between nano- and micrometers, and often of reduced dimensionality. In the phase-coherent regime at low temperatures, the conductance of these devices is governed by quantum interference effects, such as the Aharonov-Bohm effect and conductance fluctuations as prominent examples. While first measurements of quantum charge transport date back to the 1980s, spin phenomena in mesoscopic transport have moved only recently into the focus of attention, as one branch of the field of spintronics. The interplay between quantum coherence with confinement-, disorder- or interaction-effects gives rise to a variety of unexpected spin phenomena in mesoscopic conductors and allows moreover to control and engineer the spin of the charge carriers: spin interference is often the basis for spin-valves, -filters, -switches or -pumps. Their underlying mechanisms may gain relevance on the way to possible future semiconductor-based spin devices. A quantitative theoretical understanding of spin-dependent mesoscopic transport calls for developing efficient and flexible numerical algorithms, including matrix-reordering techniques within Green function approaches, which we will explain, review and employ.