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DY: Fachverband Dynamik und Statistische Physik
DY 61: Brownian Motion and Anomalous Transport
DY 61.1: Vortrag
Freitag, 13. März 2026, 09:30–09:45, ZEU/0118
Quantifying non-Markovianity via entropy production in rotational Brownian motion — •Felix Hartmann1, Finja Tietjen2, Matthias Geilhufe2, and Janet Anders1,3 — 1University of Potsdam, Institute of Physics and Astronomy, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany — 2Department of Physics, Chalmers University of Technology, 412 96 Göteborg, Sweden — 3Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
Magnetization dynamics is commonly modeled by the stochastic Landau-Lifshitz-Gilbert (LLG) equation, which describes the rotational Brownian motion of a magnetization vector on a spherical surface, and successfully explains and predicts magnetization experiments. On ultrashort timescales (∼ a few picoseconds) an extension of the LLG by an inertial term has been theoretically predicted and experimentally measured. More generally ultrafast magnetization experiments are modeled by an open-system LLG equation, which includes a memory kernel and colored noise. It has previously been reported that if classical entropy production rates become negative, the underlying dynamical evolution is non-Markovian. In this talk we employ this to detect and measure non-Markovianity in the evolution of the magnetization dynamics. We analytically show that the inertial LLG and open-system LLG equation may have temporarily negative entropy production rates. We highlight our findings by numerical calculations of the entropy production rates for the three different LLG equations under different initial conditions and field orientations.
Keywords: spin dynamics; entropy production; Brownian motion; magnetization; non-Markovianity