Extensive experimental work over the past ten years has revealed a strong spin-dependent response in molecular systems like DNA, alpha-helices, and helicene. This is in so far unexpected as organic systems usually display very weak spin-orbit effects, which are usually considered to be determinant in controlling spin-polarization effects in the absence of magnetic atoms. A common feature to all studied systems is their helical structure. In fact, the effect seems meanwhile more universal and it has been also demonstrated in inorganic systems displaying helical symmetry. Model-based Hamiltonian approaches and few atomistic first-principle calculations have suggested a delicate interplay between helical symmetry and a non-conventional spin-orbit coupling, which could be, at least partly, responsible for the observed spin sensitivity. This so called chirality-induced spin selectivity (CISS) can open the door to extensive applications of helical molecular systems in the field of spintronics, thus creating viable alternatives to currently existing semiconductor-based spintronic devices.
Goal of this Thesis will be to explore different avenues to describe spin-dependent transport in helical systems both in the coherent and incoherent (involving spin-vibration and electron-vibration scattering) and transport regimes.
The research plan will include:
1. Becoming familiar with nanoscale electron transport
2. Learning Green function and/or Master equation techniques
3. Formulation of a model Hamiltonian for helical systems including various physically relevant interaction terms
4. Numerical solution of the problem and comparison to experiments, whenever possible
Extensive experimental work over the past ten years has revealed a strong spin-dependent response in molecular systems like DNA, alpha-helices, and helicene. This is in so far unexpected as organic systems usually display very weak spin-orbit effects, which are usually considered to be determinant in controlling spin-polarization effects in the absence of magnetic atoms. A common feature to all studied systems is their helical structure. In fact, the effect seems meanwhile more universal and it has been also demonstrated in inorganic systems displaying helical symmetry. Model-based Hamiltonian approaches and few atomistic first-principle calculations have suggested a delicate interplay between helical symmetry and a non-conventional spin-orbit coupling, which could be, at least partly, responsible for the observed spin sensitivity. This so called chirality-induced spin selectivity (CISS) can open the door to extensive applications of helical molecular systems in the field of spintronics, thus creating viable alternatives to currently existing semiconductor-based spintronic devices.
Goal of this Thesis will be to explore different avenues to describe spin-dependent transport in helical systems both in the coherent and incoherent (involving spin-vibration and electron-vibration scattering) and transport regimes.
The research plan will include:
1. Becoming familiar with nanoscale electron transport
2. Learning Green function and/or Master equation techniques
3. Formulation of a model Hamiltonian for helical systems including various physically relevant interaction terms
4. Numerical solution of the problem and comparison to experiments, whenever possible