Spin and orbital fluctuations in non-equilibrium transport through quantum dots: A renormalisation-group analysis

TY - JOUR

T1 - Spin and orbital fluctuations in non-equilibrium transport through quantum dots

T2 - A renormalisation-group analysis

AU - Müller, S. Y.

AU - Koerting, V.

AU - Schuricht, D.

AU - Andergassen, S.

PY - 2010/10/19

Y1 - 2010/10/19

N2 - We study non-equilibrium current and occupation probabilities of a two-orbital quantum dot. The couplings to the leads are allowed to be asymmetric and orbital dependent as is generically the case in transport experiments on molecules and nanowires. Starting from a two-orbital Anderson model, we perform a generalised Schrieffer-Wolff transformation to derive an effective Kondo model. This generates an orbital potential scattering contribution which is of the same order as the spin exchange interaction. In a first perturbative analysis we identify a regime of negative differential conductance and a cascade resonance in the presence of an external magnetic field, which both originate from the non-equilibrium occupation of the orbitals. We then study the logarithmic enhancement of these signatures by means of a renormalisation-group treatment. We find that the orbital potential scattering qualitatively changes the renormalisation of the spin exchange couplings and strongly affects the differential conductance for asymmetric couplings.

AB - We study non-equilibrium current and occupation probabilities of a two-orbital quantum dot. The couplings to the leads are allowed to be asymmetric and orbital dependent as is generically the case in transport experiments on molecules and nanowires. Starting from a two-orbital Anderson model, we perform a generalised Schrieffer-Wolff transformation to derive an effective Kondo model. This generates an orbital potential scattering contribution which is of the same order as the spin exchange interaction. In a first perturbative analysis we identify a regime of negative differential conductance and a cascade resonance in the presence of an external magnetic field, which both originate from the non-equilibrium occupation of the orbitals. We then study the logarithmic enhancement of these signatures by means of a renormalisation-group treatment. We find that the orbital potential scattering qualitatively changes the renormalisation of the spin exchange couplings and strongly affects the differential conductance for asymmetric couplings.

U2 - 10.1209/0295-5075/92/10002

DO - 10.1209/0295-5075/92/10002

M3 - Journal article

SN - 0295-5075

VL - 92

SP - 10002

JO - Lettere Al Nuovo Cimento

JF - Lettere Al Nuovo Cimento

ER -