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SOE: Fachverband Physik sozio-ökonomischer Systeme
SOE 9: Poster - Glasses / Stat. Phys. Bio. / Networks (joint session DY/BP/CPP/SOE)
SOE 9.8: Poster
Tuesday, April 1, 2014, 09:30–12:30, P1
Non-universal dielectric properties of glasses at very low temperatures — •Annina Luck, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institut für Physik, INF227, D-69120 Heidelberg
The universal behaviour of amorphous solids at low temperatures, governed by two level tunneling systems, has long been a generally accepted fact. In the last years, however, measurements of dielectric two-pulse polarization echoes have revealed that nuclear electric quadrupole moments involved in atomic tunneling sytems can cause specific material-dependent effects in magnetic fields.
To study the possible influence of nuclear electric quadrupoles connected with atomic tunneling systems on the low frequency dielectric properties of glasses down to a temperature of 10 mK, we measured the multicomponent glass N-KZFS11, which contains 25 mass percent of tantalum oxide and a glass containing a similar amount of holmium oxide. As 181Ta and 165Ho carry very large nuclear electric quadrupole moments,these glasses seem to be ideal candidates to determine the influence of nuclear electric quadrupole moments on the physical properties of glasses at low temperatures.
Our measurements not only show a non-universal dieletric behaviour in the two glasses, but also differ significantly from various predictions of the standard tunneling model. We discuss these new findings in the framework of the tunneling model.