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Subject: ELFT HÍRADÓ
- From: Szommer Peter <szpl AT metal.elte.hu>
- To: fizinfo AT lists.kfki.hu
- Subject: [Fizinfo] Ortvay kollokvium
- Date: Fri, 20 Apr 2012 12:55:27 +0200
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- List-id: ELFT HÍRADÓ <fizinfo.lists.kfki.hu>
ELTE Fizikai Intézet
2012. április 26., csütörtök, 15 órakor
Az ELTE Pázmány Péter s. 1/A alatti épületében
földszinti 0.81 előadóban
Guido Burkard (Department of Physics, University of Konstanz, Germany):
"Spin and valley control in graphene and carbon nanotubes"
Carbon has emerged as an interesting material for coherent spin physics and spin qubits, due to both the low concentration of nuclear spins and relatively weak spin-orbit coupling. However, the localization of electrons in quantum dots in graphene is a non-trivial task due to the absence of a band gap and the related effect of Klein tunneling . However, the vicinity of the valence band also offers interesting possibilities, e.g. for non-local spin coupling . Interestingly, electrons in carbon-based quantum dots comprise a degree of freedom in addition to spin: The existence of two Dirac cones in the graphene band structure leads to the valley degree of freedom which can be coherently manipulated with oscillatory fields in a similar way as the spin in electron spin resonance (ESR). We describe this electron valley resonance (EVR) and its detection in a transport measurement . The valley degeneracy also enters the hyperfine interactions with remaining 13C nuclear spins as well as non-magnetic atomic impurities and plays an important role in the spin-valley blockade effect in double quantum dots formed in a carbon nanotube .
 B. Trauzettel, D. Bulaev, D. Loss, and G. Burkard, Nature Phys. 3, 192
 M. Braun, P. R. Struck, and G. Burkard, Phys. Rev. B 84, 115445 (2011).
 A. Pályi and G. Burkard, Phys. Rev. Lett. 106, 086801 (2011).
 A. Pályi and G. Burkard, Phys. Rev. B 80, 201404 (2009); ibid. 82, 155424 (2010).
- [Fizinfo] Ortvay kollokvium, Szommer Peter, 04/10/2012
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