PGI-1 Seminar: Dr. Zeila Zanolli
Nanoelectronics and spintronics by design
- 09.Jul.2014 11:30
- PGI Lecture Hall
Forschungszentrum Jülich, PGI-1
The research challenges of the near (1 - 6 years) and far future (7 – 15 years) focus on the quest for new materials and novel device concepts to achieve computing with low energy consumption, increased reliability and high device density. These objectives can be achieved by designing active elements and interconnects based on nanoscaled low-dimensional materials such as nanowires, carbon nanotubes, graphene and other layered materials, and complex oxides. Particular attention is devoted to the design of devices whose operating principle is not based on the electron charge but on the spin degree of freedom of the electron. To achieve these goals, computer simulations are needed to accelerate the screening of novel materials, test their physical properties in extreme conditions, and optimize their capabilities. Due to the nanoscopic size of the main device features, simulations at the atomistic level and parameter free (ab initio) are mandatory to achieve the necessary accuracy and predictive power.
In this talk, I will discuss the first principle approach to design new materials for applications in nanoelectronics and spintronics. Carbon-based nanomaterials are highly promising for spintronic applications since they can present spin diffusion lengths up to the 100 μm range and high electron velocity. However, a large spin diffusion length comes at the price of small Spin Orbit coupling, which limits the possibility of manipulating electrons via an external applied field. Besides, to achieve graphene-based devices one also needs to open its vanishing electronic gap.
One way to open a band gap in graphene and preserve high carrier mobility is to put graphene on a suitable substrate. If the substrate is magnetic, proximity interaction will induce spin polarization in the graphene and magnetic hardening of the substrate, effects that can be exploited in spintronic applications. A ferroelectric substrate will have the effect of applying an electrical polarization to the graphene allowing for gap tunability, which is a must for nanoelectronics. Another possibility is to investigate Transition Metal Dichalcogenides (TMD), which are layered materials with large Spin Orbit Coupling and that can have a finite electronic bandgap. Properly designed heterostructures of TMD with graphene have shown the potential to achieve high carrier mobility, hence paving the way for optimized device concepts for both nanoelectronics and spintronics.
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