Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 6: Superconductivity: Cryodetectors

TT 6.7: Talk

Monday, March 16, 2015, 11:15–11:30, H 2053

Characterisation of micro and nano SQUIDs at variable temperature and magnetic field — •Claudia Köhn, Jan-Hendrik Storm, Sylke Bechstein, and Thomas Schurig — Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, 10587 Berlin

SQUIDs are highly suited to investigate the magnetic properties of samples with small dimensions, such as nanoparticles, or to read out nanoelectromechanical systems (NEMS). Due to the small sample size, SQUIDs with dimensions in the μm or nm regime are desirable. These micro or nano SQUIDs should have a low noise and no hysteresis in the current-voltage-characteristic, even when operated in high magnetic fields of up to several 100 mT. To investigate such SQUID, we developed measurement setups which can simulate the measurement conditions of the intended SQUID application. The design and performance of two measurement setups will be shown and compared. One setup uses a dipstick that is immersed in liquid helium and can be evacuated to provide SQUID temperatures between 4.5 K and 10 K. The other one uses an evaporation cryostat so that the temperature can be varied from 2 K to 60 K. Both setups are equipped with coils to enable SQUID operation in variable magnetic field. To minimize noise, the output of the SQUID under test is preamplified by a SQUID series array which is operated at 4.2 K. First results of the characterisation of micro and nano SQUIDs will be presented.

This work was partly supported by the DFG under Grant No. SCHU1950/5-1 and within the European Metrology Research Program EMRP.