Micro-Raman and infrared reflectivity spectra of YBa2Cu3O7−δ deposited on LaAlO3 and stainless steel/inconel substrates

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Abstract
The motivation for this article has been to try to understand the relative phenomenological differences between the behavior of the films of the high‐temperature superconductors like YBa2Cu3O7−δ deposited on (a) relatively insulating substrates (like LaAlO3) through sputtering technique and (b) highly metallic substrates (like stainless steel and inconel) through laser ablation method. It is observed that the most prominent Raman bands on LaAlO3 substrate falling near 337, 440, and 503 cm−1 have half widths (defined as the full width at half the maximum intensity) of 22, 42, and 38 cm−1, respectively. The half width gets nearly doubled on the metallic substrates. These results have been attributed to the metal‐superconductor interfacial interactions. Further, infrared reflectance measurements and the Kramers–Kronig analysis of the spectra reveal a large difference in the conductivity of the film on LaAlO3 compared to the films on metallic substrates.