Examination of the Thermal Annealing Process in Producing YBa $_{2}$Cu$_{3}$O $_{\nabla x}$ Films and Characterization of Pressure Stabilized Oxygen Chain States
We examine the nature of thermal flow during the annealing process of a recently reported method to produce films of the high-<inline-formula><tex-math notation="LaTeX">$T_{c}$</tex-math></inline-formula> superconducting compound YBa <inline-formula><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula>Cu<inline-formula> <tex-math notation="LaTeX">$_{3}$</tex-math></inline-formula>O<inline-formula><tex-math notation="LaTeX">$_{x}$ </tex-math></inline-formula> wherein the oxygen content (<inline-formula><tex-math notation="LaTeX">$x$</tex-math> </inline-formula>) spatially varies across the length of the sample. In this context, we discuss contrasting annealing results that can be expected under differing annealing configurations—including the formation of discrete regions of pressure stabilized oxygen content associated with known lattice superstructures. We also examine characteristic energy scales associated with the corresponding normal and superconducting states of these stabilized superstructures. A relationship between ratios of the superconducting gap energy, superconducting electronic kinetic energy, and the BCS-Eliashberg coupling constant associated with each lattice superstructure is found. The near integer ratios observed suggest that the superstructures can be viewed as “quantum structural” lattice states in the sense that oxygen doping levels in between are composed of a superposition of ordered structures.