Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 18: Supraleitung: Tunneln, Josephson-Kontakte, SQUIDs
TT 18.6: Vortrag
Mittwoch, 10. März 2004, 15:45–16:00, H20
Cavity resonances in Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks under low frequency microwave irradiation — •Tobias Clauss, Takashi Uchida, Michael Mößle, Dieter Koelle, and Reinhold Kleiner — Universität Tübingen, Physikalisches Institut - Experimentalphysik II, Auf der Morgenstelle 14, 72076 Tübingen
One important problem towards the realization of THz oscillators from intrinsic Josephson junction stacks is to make the junctions in the stack to oscillate in-phase. One possibility to generate such oscillations is to excite cavity resonances by collective motion of Josephson fluxons in the stack.
So far, cavity resonances have only been observed for Bi2Sr2CaCu2O8 stacks at high external magnetic fields. We have investigated single crystal Bi2Sr2CaCu2O8 stacks at zero magnetic field under microwave irradiation with frequencies between 2 and 25 GHz. Measured current voltage characteristics show structures which can be attributed to cavity resonances. Using low temperature scanning electron microscopy to image the current distribution in the stack we find clear cavity resonances with wavelengths of some µm. We believe that the resonances are excited by the collective motion of vortex-antivortex pairs generated by the external microwave field.