Dresden 2003 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 14: Postersitzung III (Neue u. unkonventionelle Supraleiter, Anwendungen der Supraleitung, Dünne Schichten, JJs und SQUIDs, Schwere Fermionen, Kondo-Systeme)

TT 14.33: Poster

Mittwoch, 26. März 2003, 14:30–19:00, P2c

A Cryogenic Broadband Microwave Spectrometer for Solid State Studies — •Marc Scheffler and Martin Dressel — 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart

Studying the electrodynamics of solid state systems in the GHz range using resonant methods (e.g. cavities) is an established and extremely sensitive technique but limited to single resonant frequencies whereas information about the frequency dependence of electrodynamic properties is sought after in many cases (e.g. heavy fermion compounds, Kondo insulators). Up to now only very few examples of frequency-dependent measurements in the GHz range are documented. We present a new spectrometer designed to measure the surface impedance (yielding all other electrodynamical material properties like the conductivity) as a function of frequency. The setup employs the Corbino geometry and works from 45 MHz to 30 GHz in the temperature range from 1.2 K to 300 K. Our path to overcome the main difficulties of broadband microwave experiments (involving several steps of calibration) will be shown as well as measurements documenting the potential of this technique.