Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 71: Superconductivity: Cryodetectors and Cryotechnique
TT 71.6: Vortrag
Donnerstag, 23. März 2017, 16:15–16:30, HSZ 201
Electric Field Dependence of Nuclear Quadrupole driven Relaxation in Glasses at Very Low Temperatures — •Annina Luck, Andreas Schaller, Andreas Reiser, Andreas Fleischmann, and Christian Enss — Kirchhoff-Institut für Physik, Universität Heidelberg, INF 227, D-69120 Heidelberg
The universal behavior of amorphous solids at low temperatures, governed by two level tunneling systems and described by the standard tunneling model, has long been a generally accepted fact. Broadband dielectric measurements of glasses containing significant amounts of isotopes carrying very large nuclear electric quadrupole moments, have, however, revealed a relaxation mechanism involving nuclear spins, which is dominant at low frequencies and at temperatures below several hundred millikelvin. In particular, we have measured dielectric properties over eight orders of magnitude in frequency performed on the two multicomponent glasses N-KZFS11 and HY-1, containing significant amounts of tantalum and holmium respectively. As 181Ta and 165Ho both carry very large nuclear electric quadrupole moments, these glasses are ideal candidates to investigate the influence of these moments. In the regime where the nuclear spin enabled relaxation dominates, both glasses show a fundamentally different response to high electric fields, than observed in other glasses and predicted by theory. The observed saturation of the nuclear driven relaxation process at high fields allows a clear distinction between nuclear spin and phonon enabled effects and can help us gain a more detailed insight into the microscopic origin of the nuclear driven relaxation process.