Theoretical Solid State Physics

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Spin noise in QPCs

Dennis Schimmel

01.12.2016 at 12:15 

The 0.7-anomaly in the first conductance step of a quantum point contact is believed to arise from an interplay of geometry, spin dynamics and interaction effects. Previously [Bauer2014] it was shown that a one-dimensional tight-binding model with short-range interactions of intermediate strength reproduces the characteristic phenomenology of the 0.7-anomaly for the linear conductance at zero temperature and in equilibrium. Within these studies static quantities were computed using the functional renormalization group (fRG), formulated in terms of imaginary (Matsubara) frequencies. To gain access to real-frequency properties, we have formulated our fRG-scheme on the Keldysh-contour and used it to calculate dynamical quantities of a QPC, such as the local density of states, dynamical spin correlation functions, and transmission times. We have also used our Keldysh-fRG scheme to study the nonlinear conductance for a small bias voltage and discuss the effects of interactions on non-equilibrium transport.

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