Project title: Theory and simulation of spin transport in organic semiconductor devices
Supervisors: Dr Arash Mostofi, Prof Andrew Fisher and Prof Nicholas Harrison
The inclusion of spin degrees of freedom in the description of electronic structure opens such study to a wide variety of theoretically and technologically interesting phenomena, allowing new technologies to be envisioned which would require less power and provide increased data processing speeds and integration densities when compared to their electronic counterparts .
Such practical applications of spintronics (spin transport electronics) rely on developing materials with long spin coherence lifetimes, and, while the first candidates presented for these purposes were traditional, metallic, ferromagnets, there is now a parallel effort going in to developing semi-conductor (SC) spintronics. The benefits of this effort are twofold: firstly offering the possibilities in terms of computing power that SC logic brings, and secondly opening up the study to the inclusion of organic materials. Organic SCs, and in particular the ordered organic molecular crystals, represent a huge class of cheap, easily processable, versatile materials whose immense chemical flexibility can be fine-tuned through processes that exploit their strong structure-function relationships . Having low atomic numbers, organic materials also show reduced spin-orbit coupling leading to the observation of long spin-coherence lifetimes: up to five orders of magnitude larger than in metals , and theoretically reaching up to seconds .
This project investigates the spintronics properties of metal phthalocyanine (MPc) organic crystals, in which the spin transport is believed to occur via a phonon-assisted, site-to-site hopping mechanism . Preliminary experimental and theoretical studies show that this system is of particular interest for spintronics applications as it exhibits strong magnetic couplings (up to 180K) for specific transition metals and structures. The aim of the project will be to understand how structural details at the atomic scale, such as the metal species and the morphology of the crystal, affect spin transport properties at microscopic scales in the presence of external electric and magnetic fields. The theoretical work will run alongside, and in close collaboration with, the concurrent experimental programme being led by Dr Sandrine Heutz (Dept. of Materials).
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