Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 13: Poster Ia: Electron Theory (1); Magnetic Imaging (2,3); Thin Films (4-25); MSMA (26-33); Magn. Semiconductors (34-42); Magn. Half Metals and Oxides (43-60)

MA 13.2: Poster

Dienstag, 24. März 2009, 10:15–13:00, P1A

Setup of a sub-Kelvin scanning tunneling microscope — •Lei Zhang and Wulf Wulfhekel — Physikalisches Institut, Universität Karlsruhe, Wolfgang-Gaede Strasse 1, 76131 Karlsruhe, Germany

A new ultra-high vacuum sub-Kelvin scanning tunneling microscope with low noise, high stability and high energy resolution <0.1 meV was developed for the measurement of magnetic and vibronic excitations. The construction of the three stage cryostat is finished. The first stage is cooled with liquid N₂ with 10 W cooling power, the 2nd stage with liquid He⁴ with 40 mW. The third stage uses a closed-cycle Joule-Thomson refrigerator (1 mW) with either He⁴ or He³ to cool down the STM to 0.92 K (He⁴) and below 500 mK with He³. The cryostat has a very low liquid helium consumption of only 50 ml per hour and standing times of up to 200 hours. The STM has been tested at room temperature in atmosphere, and the vacuum chamber for the STM and sample preparation have been built.