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Many-body approach to spin-dependent transport in quantum dot systems
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. (Condensed Matter Theory Group)
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. (Condensed Matter Theory Group)
2002 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 88, no 22, 226601- p.Article in journal (Refereed) Published
Abstract [en]

By means of a diagram technique for Hubbard operators, we show the existence of a spin-dependent renormalization of the localized levels in an interacting region, e.g., quantum dot, modeled by the Anderson Hamiltonian with two conduction bands. It is shown that the renormalization of the levels with a given spin direction is due to kinematic interactions with the conduction subbands of the opposite spin. The consequence of this dressing of the localized levels is a drastically decreased tunneling current for ferromagnetically ordered leads compared to that of paramagnetically ordered leads. Furthermore, the studied system shows a spin-dependent resonant tunneling behavior for ferromagnetically ordered leads.

Place, publisher, year, edition, pages
2002. Vol. 88, no 22, 226601- p.
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:uu:diva-90023DOI: 10.1103/PhysRevLett.88.226601OAI: oai:DiVA.org:uu-90023DiVA: diva2:162043
Available from: 2002-10-11 Created: 2002-10-11 Last updated: 2013-05-31Bibliographically approved
In thesis
1. Non-Orthogonality and Electron Correlations in Nanotransport: Spin- and Time-Dependent Currents
Open this publication in new window or tab >>Non-Orthogonality and Electron Correlations in Nanotransport: Spin- and Time-Dependent Currents
2002 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The concept of the transfer Hamiltonian formalism has been reconsidered and generalized to include the non-orthogonality between the electron states in an interacting region, e.g. quantum dot (QD), and the states in the conduction bands in the attached contacts. The electron correlations in the QD are described by means of a diagram technique for Hubbard operator Green functions for non-equilibrium states.

It is shown that the non-orthogonality between the electrons states in the contacts and the QD is reflected in the anti-commutation relations for the field operators of the subsystems. The derived forumla for the current contains corrections from the overlap of the same order as the widely used conventional tunneling coefficients.

It is also shown that kinematic interactions between the QD states and the electrons in the contacts, renormalizes the QD energies in a spin-dependent fashion. The structure of the renormalization provides an opportunity to include a spin splitting of the QD levels by polarizing the conduction bands in the contacts and/or imposing different hybridizations between the states in the contacts and the QD for the two spin channels. This leads to a substantial amplification of the spin polarization in the current, suggesting applications in magnetic sensors and spin-filters.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2002. 101 p.
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 756
Keyword
Physics, non-orthogonality, non-equilibrium, transport, nanosystem, quantum dot, spin-dependent, renormalization, Green function, diagram technique, many-body states, Hubbard operator, electron correlations, time-dependent, Fysik, icke-ortogonal, icke-jämvikt, transport, nanosystem, kvantprick, spinberoende, renormering, Green-funktion, diagramteknik, mångkropparstillstånd, Hubbadoperator, elektronkorrelationer, tidsberoende
National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:uu:diva-2687 (URN)91-554-5418-6 (ISBN)
Public defence
2002-11-01, Polhemssalen, Uppsala, 10:15
Opponent
Available from: 2002-10-11 Created: 2002-10-11 Last updated: 2012-03-18Bibliographically approved

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Fransson, JonasEriksson, Olle

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