Spin Dependent Transport Properties of Graphene Nanoantidots: A First-principles Study
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Date
2013-03
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Addis Ababa University
Abstract
Inherently, Graphene - a perfect 20 hexagonal crystal of C-atoms, is a non-spintronics
material due to spin moment cancellation of C-atoms, especiall y, at the edges.
Spintro nics, or spin electronics, involves the study of acti ve control and manipul at ion of
spin degrees of freedom in the solid-state systems with non- equili brium spin populations.
The spins transport can be introduced either by doping or creating exotic nanostructures
of graphene such as antidots. We have performed a systematic simulational study of bare
and doped graphene nanostructures for their spin transport properti es. We studi ed the
transport properties of eight different O-shaped graphene nanoantidots (GNAOs) with
di ffe rent electrode contact configurations by using non-equili brium Green' s functions
(NEGF) in combination with the density-functional theory (OFT). Our calculations
indicate the presence of spi ntro ni city in the graphene nanoanti dot 's GNAOs' geometrical
conformations. Among the two important antidots (0 [, and O2,) , it is found that the
former is more spintronic in comparison to the latter structure. Surprisingly, Oh becomes
more spintronic when the device is connected asymmetrically to its electrodes. This spin
flip behavior is suitably ex plained in the thesis on the basis of zigzag edge spin-charge
contributions to the devices. We have also studied effect of the presence of Co atom at
center of GNAO on its spintronicity -- by comparing spin up and spin down conduction
channel s. The prospects of spin control among graphene nanostructures for spintronics
applications are also discussed in the thesis.