Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 53: Quantum Impurities and Kondo Physics

TT 53.1: Vortrag

Mittwoch, 14. März 2018, 09:30–09:45, HFT-FT 131

Quench dynamics in correlated quantum dots coupled to ferromagnetic leads — •Kacper Wrześniewski and Ireneusz Weymann — Faculty of Physics, Adam Mickiewicz University, Poznan, Poland.

We investigate the quantum quench dynamics in the single impurity Anderson model with ferromagnetic leads. The real-time evolution at finite temperatures is calculated by means of the time-dependent numerical renormalization group method in the matrix product states framework. In order to suppress the band discretization effects, we use the z-averaging trick and apply an appropriate broadening of data in collected frequency space, which is then Fourier-transformed to the real-time domain.

We study the system's response to two different types of quantum quenches: The first one relies on a sudden shift of the dot's energy level, while the second one is performed in the coupling strength to the leads. We analyze the charge and spin dynamics by calculating the time-dependent expectation values of local variables, such as the impurity's occupation number and its magnetization. We determine the time-dependence of a ferromagnetic-contact-induced exchange field and predict its nonmonotonic build-up. The influence of temperature and quench magnitude on the considered dynamics is also thoroughly discussed.