Quantum phase transition and conductivity of parallel quantum dots with a moderate Coulomb interaction

17th Russian Youth Conference on Physics of Semiconductors and Nanostructures, Opto- and Nanoelectronics

Protsenko, V.S.^1,2 ; Katanin, A.A.^1,2

Institute of Metal Physics, Kovalevskaya str. 18, Ekaterinburg

620990, Russia^1

Ural Federal University, Mira str. 19, Ekaterinburg

620002, Russia^2

关键词: Electronic interactions;    Frequency spaces;    Functional renormalization group;    High spin state;    Mean field approximation;    Quantum phase transitions;    Regularization schemes;    Step discontinuity;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/690/1/012028/pdf
DOI  :  10.1088/1742-6596/690/1/012028

来源: IOP

【 摘 要 】

We study the effects of electronic interactions on transport through parallel quantum dots connected symmetrically to leads, focusing on the case of an intermediate value of the on-site Coulomb interaction at each quantum dot. We apply both the mean-field (MF) approximation and the functional renormalization group (fRG) approach with using the Litim regularization scheme in frequency space to treat the effect of interaction and calculate the energy levels, the magnetization, the square of local spin as well as the linear conductance as a function of gate voltage. Already for intermediate values of the Coulomb interaction, the system exhibits a quantum phase transition from the parallel aligned (high spin state) to the paramagnetic (low spin) regime. This phase transition is accompanied by the appearance of the step discontinuities in the conductance, which can be observed in the experiment.