Regensburg 2002 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 2: Supraleitung: Dünne Schichten, Josephsonkontakte, SQUIDs I

TT 2.8: Vortrag

Montag, 11. März 2002, 12:15–12:30, H19

Microwave mixing in sub-micrometer bridges made from YBCO thin films. — •Konstantin Ilin and Michael Siegel — Institut fuer Schichten und Grenzflaechen (ISG), Forschungszentrum Juelich GmbH, 52425, Juelich

We present a systematic study of the YBCO thin-film microbridge response to millimeter wave radiation. The dependencies of the microwave response spectrum on bias voltage and operating temperature have been measured on samples made from the YBCO films with different thickness. Once the bias voltage exceeds the value corresponding to the first maximum of differential resistance, the value of -3dB roll-off frequency of the microbridge response drastically reduces. On the other hand at temperatures close to Tc the roll-off frequency gives a rise to about 20 GHz. For high resistive YBCO films with relatively low upper critical magnetic field the -3dB roll-off frequency is about 7 GHz even at temperatures much smaller than Tc. To explain the obtained results we consider the presence of two additive mechanisms contributing to the YBCO thin-film microbridge response to microwave radiation: vibration of the magnetic vortices and heating of the electrons and phonons. The competition between these two mechanisms defines the bias voltage and temperature dependencies of the -3dB roll-off frequency as well as the recently reported dependence of the intermediate frequency bandwidth of the YBCO hot-electron bolometer mixers on the local oscillator frequency.