Dynamic Study Of Guiding Of Vortices In YBa₂Cu₃O_7-δThin Film With Grain Boundary And Research Of Bicrystal Junction THz Mixer

Artificial pinning defects, which is usually used to control vortex motion, has been a topic of great interest in the field of vortex dynamics in recent years. Vortex is a macroscopic quantum phenomenon wherein an individual vortex is quantized. Precise control of an individual quantized vortex plays an important role in growing number of flux devices. YBa2Cu3O7-σ (YBCO) single crystals normally have a large quantity of twin bound-aries (TBs), which have been studied through numerous experimental techniques and theoretical calculations. A large amount of TBs introduce complexity to research on the precise motion of vortices. In this study, we use an individual artificial YBCO bicrystal grain boundary (GB). The principle of the bicrystal technology consists of growing a film epitaxially on a bicrystalline substrate. Owing to epitaxial growth, the substrate grain boundary is replicated in the film. This technique enables one to fabricate well-defined grain boundaries of many misorientations.GBs can locally reduce superconduction, depair current density, suppress the onset of vortex penetration, and increase power dissipation. GBs can act as easy-flow channels for vortex motion. We study guiding of vortices in a YBCO film with an individual inclined GB. Dissipative resistance in high-Tc superconductor (HTS) YBCO films caused by guiding of vortices with the GB is highly dependent on the location of the GB. We investigate the dependence of both longitudinal (Rxx) and transversal (Rxy) magnetoresistances on the orientation of the GB, temperature, current density, and magnetic field intensity. The inclined GB has a significant influence on transport properties of YBCO film.We have determined that the preferential vortices flow along the GB, which can be described as a channel flow state. An increase in temperature or magnetic field intensity leads to the destruction of the guided motion of vortices, and both longitudinal and transversal magnetoresistances are close to the properties of normal HTS films without GB. We present experimental measurements of the guiding effect in YBCO film with an individual GB oriented at the angle a=30°with respect to the direction of the applied current. We can also develop a significant magnetic-field temperature phase diagram in the presence of the GB, which reflects the important role of the GB in vortex transport properties of HTS.We used EB to fabricate800nm wide YBCO bicrystal junctions, and we used double reduction methord to fabricate TIBaCaCuO bicrystal junctions. Due to high temperature superconducting (HTS) Josephson junction has excellent high frequency and nonlinear properties, it can be used in HTS frequency mixer. HTS Josephson junction mixer has much excellence, including its high sensitivity and harmonic, low local oscillator frequency and microwave power, low noise and wide frequency band.