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Electric Transport Phenomena in Mesoscopic Devices

English title Electric Transport Phenomena in Mesoscopic Devices
Applicant Schönenberger Christian
Number 124670
Funding scheme Project funding (Div. I-III)
Research institution Departement Physik Universität Basel
Institution of higher education University of Basel - BS
Main discipline Condensed Matter Physics
Start/End 01.04.2009 - 31.03.2011
Approved amount 636'482.00
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Keywords (10)

Electronic Properties of Nanostructures; Charge and Spin Transport in Nanostructures; Physics in Reduced Dimensions; Quantum Transport; Nanoelectronics; Spintronics; Quantum Electronics; Carbon Nanotubes; Semiconducting Nanowires; Graphene

Lay Summary (English)

Lead
Lay summary
The ever growing interest in low dimensional systems, such as one-dimensional wires and zero-dimensional quantum dots is due to the unique transport properties of charge and spin currents in these systems. We aim at the understanding of fundamental transport phenomena in low-dimensional hybrid conductors using carbon nanotubes (CNTs), semiconducting nanowires and graphene layers as interacting model systems. To these conductors we fabricate normal (N) metal, superconducting (S) and ferromagnetic (F) electrodes. This provides a large space in which novel phenomena in correlated spin and charge transport appear. Our proposal spans from tunable exchange interaction in quantum dots to unconventional Josephson junctions.The present proposal has its focus on spin-transport (spintronics) and on the supercondcuting proximity effect in quantum dots (qdots) made from either carbon nanotubes (CNTs), semiconducting nanowires (NWs) or graphene. The beauty of CNTs and NWs is that hybrid qdots with N, S, and F contacts can be realized. This is a truly novel opportunity, since similar hybrid qdots are very difficult (or impossible) to fabricate in semiconductor heterostructures. Among other things, the opportunities include gate-tunable supercurrent and SQUIDs, unconventional Josephson effect in S-qdot-S devices and tunable magneto-resistance, spin accumulation and exchange field in F-qdot-F devices. Whereas the field of superconductivity and ferromagnetism seem quite different, on a conceptional level there is a clear common denominator: we are interested in the proximity effect in low dimensional objects, in particular in qdots, in which Coulomb correlations and level spectra matter. If such a qdot is contacted by a superconductor one wonders to what extent the pair-correlation function of the S contact can penetrate into the qdot. This is historically termed as "the proximity effect". If the qdot is contacted by an F contact, on the other hand, the induction of an exchange field on the qdot can be seen as the ferromagnetic proximity effect. In addition to this equilibrium part, a non-equilibrium spin accumulation may appear in the qdot when a spin-dependent current is present.Information on the group can be found under: http:\\www.unibas.ch\phys-meso
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
134619 Electric Transport Phenomena in Nanoscaled Devices 01.04.2011 Project funding (Div. I-III)
116621 Electric Transport Phenomena in Mesoscopic Devices 01.04.2007 Project funding (Div. I-III)
111379 NCCR Nanoscale Science: Impact on Life Sciences, Sustainability, Information and Communication Technologies (phase II) 01.06.2005 National Centres of Competence in Research (NCCRs)
129378 ENTS: Entangled spin pairs in graphene 01.03.2010 Project funding (special)

Abstract

The ever growing interest in low dimensional systems, such as one-dimensional wires and zero-dimensional quantum dots is due to the unique transport properties of charge and spin currents in these systems. We aim at the understanding of fundamental transport phenomena in low-dimensional hybrid conductors using carbon nanotubes (CNTs), semiconducting nanowires and graphene layers as interacting model systems. To these conductors we fabricate normal (N) metal, superconducting (S) and ferromagnetic (F) electrodes. This provides a large space in which novel phenomena in correlated spin and charge transport appear. Our proposal spans from tunable exchange interaction in quantum dots to unconventional Josephson junctions.The present proposal has its focus on spin-transport (spintronics) and on the supercondcuting proximity effect in quantum dots (qdots) made from either carbon nanotubes (CNTs), semiconducting nanowires (NWs) or graphene. The beauty of CNTs and NWs is that hybrid qdots with N, S, and F contacts can be realized. This is a truly novel opportunity, since similar hybrid qdots are very difficult (or impossible) to fabricate in semiconductors based on grown heterostructures. Among other things, the opportunities include gate-tunable supercurrent and SQUIDs, unconventional Josephson effect in S-qdot-S devices and tunable magneto-resistance, spin accumulation and exchange field in F-qdot-F devices. Whereas the field of superconductivity and ferromagnetism seem quite different, on a conceptional level there is a clear common denominator: we are interested in the proximity effect in low dimensional objects, in particular in qdots, in which Coulomb correlations and level spectra matter. If such a qdot is contacted by a superconductor one wonders to what extent the pair-correlation function of the S contact can penetrate into the qdot. This is historically termed as “the proximity effect”. If the qdot is contacted by an F contact, on the other hand, the induction of an exchange field on the qdot can be seen as the ferromagnetic proximity effect. In addition to this equilibrium part, a non-equilibrium spin accumulation may appear in the qdot when a spin-dependent current is present.Information on the group can be found under: http:\\www.unibas.ch\phys-meso
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