Regensburg 2004 – scientific programme

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TT: Tiefe Temperaturen

TT 30: Postersitzung IV: Kritische Ph
änomene, Quantenstörstellen, niederdimensionale Systeme

TT 30.41: Poster

Thursday, March 11, 2004, 14:30–19:00, Poster A

Measurements of the low-frequency elastic properties of glasses with double paddle oscillators and SQUID based readout — •X. Cao¹, M. Layer¹, A. Fleischmann¹, C. Enss², and S. Hunklinger¹ — ¹Kirchhoff-Institut fuer Physik, Heidelberg University, Im Neuenheimer Feld 227, D-69120 Heidelberg — ²Brown University, Providence, RI 02912, USA

The double paddle resonator is a common tool for investigating the low-frequency elastic properties of solids. With the special oscillator geometry the background damping due to clamping is very small compared with the vibrating reed method. At low temperatures, the changes in the sound velocity and the internal friction of amorphous solids are dominated by the interaction between the phonons and the tunnelling systems. In order to avoid nonlinear response from the system, the deformation amplitude used in the measurements has to be very small. To achieve high sensitivity we incorporated an inductively complied readout based on a DC-SQUID, whose performance has been shown to exceed that of the conventional capacitive method in the vibrating reed measurements. With this combination, it is possible to study the acoustic properties of glasses at ultralow temperatures (T<5 mK). The technique and first measurements are presented.