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DY: Fachverband Dynamik und Statistische Physik

DY 7: Statistical Physics (General) I

DY 7.5: Vortrag

Montag, 16. März 2020, 11:00–11:15, ZEU 160

A microscopic model for the computation of dielectric relaxation phenomena in composite systems — •Sujith Reddy Varakantham and Herbert Kliem — Institute of Electrical Engineering Physics, Saarland University, Saarbrücken, Germany

Dielectric relaxation in single phase and composite systems is computed using a microscopic model comprised of thermally activated dipoles fluctuating in double well (DW) potentials. The dipoles interact with each other by their Coulomb forces, thereby influencing mutually the properties of the DWs. To find the time dependent polarization response, a Monte-Carlo simulation method is employed by combining deterministic calculation of potentials with a probabilistic random number. By the interaction, the polarization response changes from Debye to stretched exponential. Afterwards, the time dependent polarization is transformed into the frequency domain. Two single systems with different DW barrier heights, i.e., different relaxation times and also with different distribution of barrier heights are computed first. Then the systems are combined in series connection as well as in embedded systems. While the individual systems exhibit stretched exponential responses with varied stretching factors corresponding to fixed and distributed barrier heights of the DWs, composed systems, on the other hand, show an intermediate behavior comprising both responses. To validate our simulation results, experiments are carried out using a series combination of aluminium and hafnium oxides, each having different dielectric responses. Our simulation results are in agreement with the experimental findings