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 14.32: Poster

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

Near field spectroscopy in the frequency range from 30 GHz to 1.5 THz — •Stephan Mair, Bruno Gompf, and Martin Dressel — 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart

Today several modern areas of condensed matter physics like low-dimensional conductors and superconductors or electronically correlated systems call for investigations in the low energy range of the electromagnetic spectrum. Unfortunately the spatial resolution is generally restricted by Abbe’s diffraction limit, which in this frequency range is as large as 5 mm to 0.1 mm. On the other hand the growth of large crystals of these exotic materials is rather difficult, thus it is not always possible to grow monocrystalline areas with dimensions larger than the wavelength.

To overcome this problem, we have designed a near-field spectrometer which combines a high spatial resolution of up to 1 µm with a large frequency range from 30 GHz to 1.5 THz. To control the distance between sample and pinhole and to examine the sample area in situ we use an image-processing confocal microscope. Furthermore the whole near field unit is incorporated in an optical cryostat, which allows temperature dependent measurements in the range from 4 K to 400 K.

In our contribution we will present the design of our system, discuss the problems in measuring the low near-field signals and show first results.