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[Fizinfo] Ortvay kollokvium

Chronological Thread 
  • From: Szommer Peter <szpl AT>
  • To: fizinfo AT
  • Subject: [Fizinfo] Ortvay kollokvium
  • Date: Fri, 20 Apr 2012 12:55:27 +0200
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  • List-id: ELFT HÍRADÓ <>

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"

Kivonatos ismertetés:

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 [1]. However, the vicinity of the valence band also offers interesting possibilities, e.g. for non-local spin coupling [2]. 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 [3]. 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 [4].

[1] B. Trauzettel, D. Bulaev, D. Loss, and G. Burkard, Nature Phys. 3, 192

[2] M. Braun, P. R. Struck, and G. Burkard, Phys. Rev. B 84, 115445 (2011).

[3] A. Pályi and G. Burkard, Phys. Rev. Lett. 106, 086801 (2011).

[4] A. Pályi and G. Burkard, Phys. Rev. B 80, 201404 (2009); ibid. 82, 155424 (2010).

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