Non-Orthogonality and Electron Correlations in Nanotransport : Spin- and Time-Dependent Currents

• 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.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

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

Physics

Fysik

Fysik

Physics

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