Microwave emission due to anisotropic quasiparticle injection into an ErBa2Cu3Oy superconductor

We report the observation of microwave emission and the de measurements on tunnel injection of quasiparticles into a ErBa2Cu3Oy (EBCO) thin film using the samples with antenna geometry which are nearly free from the parallel overlapping effect of the injector current and the thin film current. The i njector consists of two EBCO/insulator/Au (S/I/N) gate junctions. The sampl es were fabricated by lift-off photolithography technique. The microwave em ission intensity from the junction was measured under the condition of broa dband non-resonant matching using a superheterodyne radiometric receiver at frequencies f(REC) = 36 GHz and 47 GHz. The detected microwave emission po wer increased nearly linearly with the injection current. The emitted power was greater for the higher receiving frequency. The observed maximum emitt ed broad band spectrum power at frequency f(REC) = 47 GHz was about 10 pW f or an integrating time of 1 sec The phenomenon is discussed in terms of the nonequilibrium dynamics together with the ionic nature of oxide supercondu ctor.