Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 6: TR: Nanoelectronics II: Spintronics and Magnetotransport
TT 6.16: Talk
Monday, March 22, 2010, 18:00–18:15, H19
Frequency-Dependent Spin Conductance and Spin Noise of Quantum Dots in the Kondo Regime — •Ireneusz Weymann1,2, Catalin Pascu Moca3, and Gergely Zarand3 — 1Physics Department, ASC, and CeNS, Ludwig-Maximilians-University, Theresienstrasse 37, 80333 Munich, Germany — 2Physics Depertement, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan, Poland — 3Department of Theoretical Physics, Institute of Physics, Budapest University of Technology and Economics, H-1521 Budapest, Hungary
We analyze the equilibrium and non-equilibrium frequency-dependent spin noise and spin conductance of a quantum dot in the Kondo regime. The equilibrium spin noise is characterized by two universal functions that we determine perturbatively for large frequencies, and compute numerically at zero temperature using numerical renormalization group.
The parallel and antiparallel noise components show markedly different frequency dependence. The antiparallel spin conductance develops a resonance for frequencies of the order of the Kondo temperature as a result of dynamical spin accumulation. For temperatures well above the Kondo scale, a low-frequency anomaly appears in the spin current correlations below the Korringa relaxation rate.