Regensburg 2016 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 50: Glasses

DY 50.3: Vortrag

Donnerstag, 10. März 2016, 10:15–10:30, H48

Relevance of Nuclear Quadrupoles to the Low Temperature Dielectric Properties of Glasses — •Annina Luck, Benedikt Frey, Wiebke Scholz, Guido Homann, Anne Zeissner, Nils Hauff, Philipp Wesp, Andreas Reiser, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institut für Physik, Universität Heidelberg, 69120 Heidelberg

The standard tunneling model based on two level systems describes many properties of solids at low temperatures. Over the years the measurements of dielectric and acoustic properties have, however, shown significant deviations from predictions made by this model. Despite enormous efforts these deviations are yet unexplained.
One aspect which is missing in the prediction of low frequency dielectric properties by the tunneling model is the relevance of nuclear spins, which has been proven to be important in dielectric polarization echo experiments at 1 GHz. Despite of this, modelling the consequences of this effect on the low frequency dielectric and acoustic susceptibility has proven difficult.
In order to experimentally investigate the role of nuclear quadrupoles in the dielectric susceptibility we have investigated multiple glass samples containing elements with different quadrupole moments in a wide frequency range spanning from Hz to GHz.
We have found clear indications for a novel nuclear spin driven two level system relaxation process at very low temperatures.