Microwave oscillations in a superconducting tunnel mesa structure under conditions of spin filtration
K.Y. Constantinian, G.A. Ovsyannikov, Yu.V. Kislinsky, A.M. Petrzhik, A.V. Shadrin, and V.V. Demidov
Institute Radio Engineerings and Electronics of the Russian Academy of Science, Moscow, 125009, Russia
Received November 3, 2017
The process of microwave oscillations in thin-film tunnel type mesa structures consisting of a cuprate superconducting YBa2Cu3O7–x epitaxial film, a barrier layer of manganite LaMnO3 and an upper superconducting Au/Nb bilayer has been experimentally studied. The frequency of the detected microwave oscillations is tuned by the bias voltage and the external magnetic field, and the oscillations linewidth is 50 MHz. At the mesa structures, conductivity peaks were observed at voltages corresponding to the niobium energy gap and the resistance peak at V = 0. With decreasing temperature below the critical temperature of niobium, an increase in the resistive peak at zero bias and a tunneling 10% magnetoresistance at a magnetic field H = 0.5 kOe were observed due to the influence of a spin-polarized current on characteristics of the mesa structure. The magnetic characteristics of the manganite interlayer in mesa structures were investigated by FMR spectroscopy on structures fabricated without the superconducting niobium film.
PACS: 74.72.–h Cuprate superconductors;
Key words: superconducting heterostructures, tunneling, spin-polarized current, magnetoresistance, micro-wave oscillations.
Published online: January 25, 2018