Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 89: Disordered Quantum Systems

TT 89.2: Vortrag

Donnerstag, 15. März 2018, 11:45–12:00, HFT-FT 131

Low Temperature Properties of Amorphous Polymers containing Nuclear Quadrupole Moments — •Benedikt Frey, Nicole Assmann, Patrick Schygulla, Annina Luck, Andreas Fleischmann, Andreas Reiser, and Christian Enss — Kirchhoff-Institute for Physics, Heidelberg University, D-69120 Heidelberg

The low temperature properties of amorphous solids are governed by atomic tunneling systems and can be described by the phenomenological standard tunneling model (STM). In recent years, two-pulse polarization echoes and dielectric measurements, have revealed the importance of nuclear electric quadrupole moments for the tunneling dynamics. Dielectric properties of the multicomponent glasses N-KZFS11 and HY-1, containing atoms with very large nuclear electric quadrupole moments, show significant deviations from the STM. This can be interpreted as a new quadrupole mediated relaxation process, which dominates the relaxation rate at low temperatures.

In order to further study this relaxation mechanism, we measured the low temperature dielectric properties of several amorphous polymers, which contain nuclear quadrupole moments with quadrupole splittings ranging from 30 MHz to 250 MHz. The well known chemical structure of these polymers and the large variety of chemically accessible compositions enables systematic investigations. We present first results from dielectric measurements of three different polymers at frequencies between 60 Hz and 140 MHz. In particular, the brominated samples show strong deviations from the STM at low temperatures and low frequencies.