FWF - Spin-Selektiver Quantent - Spin-Selective Quantum Transport through Heterointerfaces

Project: Research project

Description

Giant magneto-resistance (GMR) and tunneling magneto-resistance (TMR) arguably are the most spectacular examples to demonstrate the potential of spintronics for realizations of novel fast and low-energy devices. Driven by potential technological applications, spintronics has indeed become a florishing field of research which has developed rapidly into a hot topic of solid-state physics, posing challenges to electron transport physics, ultra-fast spectroscopy, and nano-magnetism alike. While traditional devices have mainly been based on one or two classes of materials, such as semiconductors and oxides in conventional electronic devices, superconductors and insulators in SQUIDS, or ferromagnetic materials, spintronic effects are based on (nano- and hetero) structures which generally are synthesized from materials with vastly different host properties, consisting of a combination of nonmagnetic layers, such as semiconductors, insulators, and metals, and magnetic layers, such as semi-magnetic semiconductors, ferromagnets, half-metallic ferromagnets, and/or antiferromagnets. A sound understanding of the behavior of the spin degree of freedom of charge carriers (transport electrons and holes) at heterointerfaces is therefore one of the key prerequisites for a microscopic understanding of basic processes in spintronics, such as TMR, GMR, spintorque effects, and - particularly- spin injection.
Here we propose a theoretical study of spin-selective charge transport through heterointerfaces between semiconductors, semi-magnetic semiconductors, insulators, and (half-metallic) ferromagnets. We set up a theory which combines electronic structure calculations with (steady-state) quantum transport based on Green's function theory to study spin-selective charge transport through (multiple) heterointerfaces. Self-consistent transport models of increasing complexity are developed. Electronic structure calculations for halfmetallic ferromagnets are performed within the localdensity approximation plus dynamical mean-field theory (LDA+DMFT) providing an input for the transport calculations. A key ingredient for transport calculations, the band-offsets between different materials, will be determined by the former.
StatusFinished
Effective start/end date1/10/0930/09/12