Dresden 2003 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 12: Mesoskopische Systeme II

TT 12.6: Vortrag

Mittwoch, 26. März 2003, 16:00–16:15, HSZ03

Multistability effects in a quantum dot coupled to a Holstein phonon — •Andrei Komnik¹ and Alexander O. Gogolin² — ¹Physikalisches Institut, Albert-Ludwigs-Universität Freiburg,D-79108 Freiburg, Germany — ²Department of Mathematics, Imperial College, 180 Queen’s Gate,London SW7 2BZ, United Kingdom

We investigate transport through molecular single state quantum dots coupled to a Holstein-type phonon and contacted by two electrodes. An effective action for the phonon is derived in the Born-Oppenheimer approximation. For a spinless system in the equilibrium a bistability regime is found at certain values of the gate voltage. At finite transport voltage a bistable regime can be accessed even without the additional gate electrode and a hysteretic behaviour in the I−V emerge. A tristable regime is found to exist in the non-equilibrium in a spinless system and in the equilibrium system with spin. In case the non-interacting leads are replaced by the Luttinger liquids the criteria for observation of the bi- and tristability are found by means of mapping to Kondo problem. For the special interaction strength the phonon effective action is written down explicitly and analysed. Implications for the transport experiments on molecular quantum dots are discussed.