Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 30: Poster Session: Disordered Quantum Systems
TT 30.5: Poster
Montag, 12. März 2018, 15:00–19:00, Poster B
Low Frequency Acoustic and Dielectric Measurements of a Polymer Glass Containing Nuclear Quadrupole Moments — •Patrick Schygulla, Andreas Reiser, Annina Luck, Benedikt Frey, Nicole Assmann, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institut für Physik, Universität Heidelberg, INF 227, D-69120 Heidelberg
Recent studies of glasses with nuclear electric quadrupole moments such as N-KZFS11 and HY-1 have revealed deviations in the dielectric function from the predictions of the standard tunneling model (STM), in particular an additional relaxational contribution.
We used a double paddle oscillator for acoustic and a capacitance bridge for dielectric measurements in order to investigate the elastic and dielectric susceptibility respectively at temperatures ranging from 7 to 700 mK and at frequencies between 60 Hz and 16 kHz. The examined polymer glass, FR-122P, has an atomic bromine content of 11 % with a well defined hyperfine level splitting of νQ≈ 250 MHz. While at higher temperatures one-phonon processes can explain the data, below the temperature of the maximum the resonant contribution to the change of sound velocity is hardly visible and in the loss data a constant contribution was found in contrast to the expected T3-dependence. The measured results are compared to numerical calculations of different extensions to the STM accounting for the presence of quadrupole moments. Also, first results are discussed from a newly designed experimental setup allowing for selectively saturating the quadrupolar transition of the nuclei during the measurement.