Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 4: Disordered Quantum Systems

TT 4.3: Vortrag

Montag, 16. März 2020, 10:15–10:30, HSZ 204

Dielectric Polarization Echoes of Glasses Containing Large Nuclear Quadrupole Moments — •Andreas Schaller, Andreas Reiser, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institute for Physics, Heidelberg University, D-69120 Heidelberg

Many properties of amorphous solids at low temperatures can be explained by the standard tunneling model, which is based on atomic tunneling systems, described as two-level systems. Tunneling systems with an electric dipole moment couple resonantly to electric fields and can thus be studied using dielectric two-pulse polarization echoes to learn about their dynamics and coherence. Measurements of the dielectric constant, sound velocity, and dielectric polarization echoes of glasses containing atoms carrying nuclear quadrupole moments revealed unexpected characteristics, such as magnetic field dependencies, which are not observed in glasses without nuclear moments. Furthermore, measurements of the dielectric constant of glasses with large nuclear quadrupole moments point towards a so far unconsidered relaxation process.

We present results of dielectric two-pulse polarization echo measurements carried out on different multi-component glasses and polymers containing large nuclear quadrupole moments. For all these samples the two-pulse-echo amplitude is small and the decay occurs on a shorter timescale compared to samples containing no or just small nuclear quadrupole moments. We compare the results to simulations obtained by a Monte Carlo method approach.

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