Comparison of nanostructures formed on Nb using fs near-IR and ps UV pulsed lasers

Abstract

It is well known that the use of ultrashort (fs) pulsed lasers can induce the generation of (quasi-) periodic nanostructures (LIPSS, ripples) on the surface of metallic samples. Such nanostructures have also been observed in sample's surfaces that have been irradiated with UV lasers with a pulse duration of 300 ps. In this work, we compare the characteristics of these nanostructures on 25-micrometer thick Nb sheets induced by different pulsed lasers, and we analyze the influence of the different parameter conditions that were selected for the laser processing. In addition to conventional continuous or burst mode processing configurations, a meandering laser line scanning has also been investigated. This configuration allows the processing of large areas with a more uniform distribution of nanostructures at the surface. The influence of these nanostructures on the superconducting properties of Nb has also been investigated. With this aim, magnetic hysteresis loops have been measured at different temperatures to analyze how these laser treatments can affect the flux pinning behavior and, in consequence, their critical current values.