Regensburg 2010 – scientific programme

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SYDI: Symposium SKM Dissertation Prize 2010

SYDI 1: SKM Dissertation Prize 2010

SYDI 1.4: Invited Talk

Tuesday, March 23, 2010, 15:00–15:30, H10

Quantum transport in nanostructures: from numerical algorithms to spintronics in graphene — •Michael Wimmer — Institut für Theoretische Physik, Universität Regensburg, Germany — Instituut Lorentz, Universiteit Leiden, The Netherlands

When device dimensions become comparable to the phase coherence length of electrons, quantum effects lead to a vast number of different transport phenomena. In this talk, I will focus on two aspects of quantum transport: numerical algorithms to calculate quantum transport properties, and the generation of spin currents in graphene.

In principle, there are well-established theoretical frameworks for the numerical calculation of quantum transport properties. However, the application of these frameworks to a specific system faces difficulties that often are solved individually for each problem. I will highlight these difficulties and present generic solutions that allow for the solution of quantum transport problems in arbitrary systems.

Making use of these numerical techniques as well as analytical models, I will then discuss the generation of spin currents in graphene. Graphene nanoribbons oriented close to the “zigzag” direction support edge states that have been predicted to be magnetic. I will show how edge roughness can be used to generate a finite spin conductance. The effects of phase coherence also lead to a universal value of the spin conductance fluctuations. A finite spin conductance is a prerequisite for spintronics applications, and may also serve as an all-electrical detection method of the edge magnetism in graphene that has been elusive experimentally so far.