Regensburg 2013 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 17: Glasses III (joint session with CPP, DY)

DF 17.1: Vortrag

Mittwoch, 13. März 2013, 12:30–12:50, H11

Nonlinear dielectric response of glass-forming systems — •Thomas Bauer, Peter Lunkenheimer, Stefan Kastner, and Alois Loidl — Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg

In the present contribution, we report a thorough investigation of Type A and other glass-forming liquids by nonlinear dielectric spectroscopy. This is done by comparing and quantifying the difference of high- and low-field permittivity as well as by the determination of higher harmonics after applying a high ac field up to 849 kV/cm. In earlier works [1,2], a strong increase of the dielectric loss was found at the high-frequency flank of the α-relaxation peak while the field dependence was negligible at low frequencies. This finding is consistent with the box model, assuming correlated dielectric and thermal relaxation times within dynamical heterogeneities. We show measurements extending into the frequency region of the so-called excess wing that indicate a complete lack of this nonlinear effect for this spectral feature. In addition, we report the higher-order response of glycerol and propylene carbonate for a broad temperature range and various electric fields. The third-order susceptibility shows a significant hump, that can be ascribed to molecular correlations [3] and cannot be explained by trivial saturation effects of the dipolar polarization, known since long.

[1] R. Richert and S. Weinstein, Phys. Rev. Lett. 97, 095703 (2006).

[2] L.-M. Wang and R. Richert, Phys. Rev. Lett. 99, 185701 (2007).

[3] C. Crauste-Thibierge, C. Brun, F. Ladieu, D. L’Hôte, G. Biroli, and J-P. Bouchaud, Phys. Rev. Lett. 104, 165703 (2010)