A new concept of electronic devices based on type II superconductor YBCO films with channel for motion of magnetic vortice

Abstract

The critical superconducting current is one of the most important characteristics of superconducting films if films are applied in low- and high-power superconducting electronic and/or optoelectronic devices. If the superconductor is under supercritical current, then its diamagnetic properties depend on the amplitude of the current self-produced magnetic field, which results in the first flux penetration into a mixed-state superconductor in the form of Abrikosov magnetic vortices, and on a balance between the pinning Fp and the Lorentz FL forces acting on these magnetic vortices. (Here, the mixed state is the state in which the superconducting and normal phases of the superconductor material can coexist together.) The increase in FL results in the onset of the critical current density in the superconducting devices and the onset of an energy dissipative state in the superconductor caused by the nucleation and motion of Abrikosov magnetic vortices. The superconducting properties of type II superconductor cuprates are a function of the ambient temperature, the amplitude and direction of an external magnetic field, and the level of doping by oxygen. Current work demonstrates the potential to control the balance between Fp and FL through the artificial introduction of partially decomposed by oxygen 5-um-wide and 50-um-long line (channel for a motion of Abrikosov magnetic vortices) in 50 x 100 x 0.3 um3 (width x length x thickness) YBa_2Cu_3O_(7-x) (YBCO) devices. Due to the inhomogeneous distribution of oxygen concentration in the channel, our devices exhibit nonlinear stepped-like current-voltage (I-V) characteristics resulting from a periodic on/off of vortex motion in the channel at temperatures below the T_c^on of the superconductor, which is optimally doped by oxygen. The technology of nonuniform oxygen concentration profiles in the YBCO superconducting film and the origin of the stepped-like I-V characteristic of the YBCO devices biased with supercritical current at temperatures below T_c^on are presented and discussed. Our results can be applied to developing advanced superconducting electronic and optoelectronic devices with superconducting properties of the device driven by precisely controlled internal (i.e. self-produced by the current) and/or external magnetic fields.