Abstract
We report on current transport and magnetism in hybrid superconducting mesa-structures prepared from epitaxial superconductor YBa2Cu3O7-δ and manganite LaMnO3 thin films. Superconducting Au-Nb bilayer was the top electrode. Measurements of magnetic resonance in heterostructure with the only Au top electrode (without Nb) showed ferromagnetic state close to Curie temperature of LaMnO3, 150 K. A spin filtering was revealed by measurements of tunneling magneto-resistance. Mesa-structures had no superconducting current even at reduced temperature T=300 mK and the smallest manganite interlayer thickness, dM=5.6 nm. Varying the external magnetic field |H|<10 Oe and dc bias current |I|<0.5 mA the microwave generation with power P <1 pW with a line-width of order 50 MHz was observed in GHz frequency band. The frequency of generation could be tuned by the biasing current with a rate 1013 Hz/A. The impact of spin polarized current on microwave generation is discussed taking into account the asymmetry of oscillation amplitudes over the applied magnetic field.
Highlights
Superconducting structures with a spinpolarized current have attracted increasing interest in view of the prospects for their use in spintronics and novel elements of microwave electronics
Interaction of superconductivity and magnetism was studied in hybrid structures comprised from superconductors (S) and ferromagnetic materials (F), tunnel junctions with a ferromagnetic barrier [1, 2] and etc
With an increase of dc bias voltage above 3 mV, the conductivity of the mesa-structure no longer depends on magnetic field [16]
Summary
Superconducting structures with a spinpolarized current have attracted increasing interest in view of the prospects for their use in spintronics and novel elements of microwave electronics.
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