Syntheses And Properties Of Practical Nitride And YBa₂Cu₃O_6+x Superconducting Thin Films

Thin film superconductors provide an important material platform for investigating technological applications.They play crucial roles in elucidating the underlying physics mechanism of superconductors in general.This dissertation focuses on the transition metal nitride superconductors and high-transition temperature superconductor YBa₂Cu₃O_6+x（YBCO）films,using laser pulse deposition and magnetron sputtering material synthesis techniques.A complete phase diagram of zirconium nitride is constructed by growing series of ZrN_x thin films with different nitrogen concentrations.Employing a variety of experimental measurements,including electrical transport,Hall effect,magnetism,Raman spectroscopy,THz spectroscopy,and scanning tunneling electron microscopy,and combining first-principles calculations,we explained the evolution of the superconducting and normal states in ZrN_x thin films.For YBCO superconducting thin films,we obtained YBCO with high T_c,high crystallinity,and high external ductility by optimizing the growth process.The surface condition of the extremely thin YBCO film was optimized to meet the needs of superconducting quantum interference devices and superconducting single-photon detectors.The followings are a brief introduction to the achievements of this dissertation:（1）Series of ZrN_x thin films with different nitrogen concentration were grown using pulsed laser deposition technique.The effects of different growth conditions on ZrN_x thin films were studied,and the growth process was optimized.ZrN_x thin films with different N content have a well-defined structure.Furthermore,semiconducting ZrN_xO_y thin films were grown by magnetron sputtering,which can be used for applications such as thermometers at low temperatures and in strong magnetic fields.（2）Through the transport characterization of ZrN_x thin films,we found that superconducting dome forms as a function of N concentration,which resembles those for high transition temperature superconductors.Employing a variety of experimental measurements and theoretical analysis,we found that the change in the superconductivity of ZrN_x is controlled by the charge localization and electro-phonon coupling strength.（3）The material synthesis conditions that affect the superconductivity,crystallinity,epitaxy and surface roughness of YBCO thin films grown by pulsed laser deposition were systematically studied.We achieve high-quality thick and thin YBCO films.The thicker YBCO films aiming for microwave device applications have relatively high Tc and superconducting percentage volume,with a microwave surface resistance of less than 1mΩ@10GHz,77K.YBCO thin films aiming for Josephson junction applications are optimized for surface conditions.