Systemic measurements show that there is no 3D to 2D crossover in the reduction of the superconducting transition temperature Tc in Nb thin films. This result is consistent with all previous measurements while it is c...Systemic measurements show that there is no 3D to 2D crossover in the reduction of the superconducting transition temperature Tc in Nb thin films. This result is consistent with all previous measurements while it is contrary to the prevailing understanding based on the interplay between proximity, localization, and lifetime broadening. Our study indicates that the decrease of Tc can be interpreted by the combined effects of electron-phonon coupling parameter λ and the defect scattering rate pw, being uniquely determined by their ratio λ/ρw. Other factors such as film thickness and irradiation do not produce additional effects beyond these two parameters.展开更多
The growth of Nb thin films on Si（100） substrates by different laser fluences （4-15 J/cm2） was reported, The pulsed Nd：YAG laser deposition （PLD） under influence of laser fluence on ablation rate and deposition...The growth of Nb thin films on Si（100） substrates by different laser fluences （4-15 J/cm2） was reported, The pulsed Nd：YAG laser deposition （PLD） under influence of laser fluence on ablation rate and deposition rate was discussed. X-ray diffraction （XRD） investigations of the deposited films showed an amorphous structure. The droplet density on the film surface observed by scanning electron microscopy （SEM） analyses was extremely low. It was experimentally proved that the droplets on the film surface originated from liquid phase on the target surface, Profilometric measurements of the deposited Nb films revealed a substantial asymmetry in the film thickness related to the plume deflection effect. The measured electrical resistivity of the Nb film was higher than that of high purity Nb bulk. The present investigations of ablation and deposition process of Nb thin films are related to its potential application in superconducting radio-frequency （SRF） cavities.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11104331the National Basic Research Program of China under Grant No 2011CB921702
文摘Systemic measurements show that there is no 3D to 2D crossover in the reduction of the superconducting transition temperature Tc in Nb thin films. This result is consistent with all previous measurements while it is contrary to the prevailing understanding based on the interplay between proximity, localization, and lifetime broadening. Our study indicates that the decrease of Tc can be interpreted by the combined effects of electron-phonon coupling parameter λ and the defect scattering rate pw, being uniquely determined by their ratio λ/ρw. Other factors such as film thickness and irradiation do not produce additional effects beyond these two parameters.
基金supported partially by the Italian Ministry of Research in the framework of FIRB-Fondo per gli Investimenti della Ricerca di Base(Project no.RBFR12NK5K)the Italian National Institute of Nuclear Physics(INFN)
文摘The growth of Nb thin films on Si（100） substrates by different laser fluences （4-15 J/cm2） was reported, The pulsed Nd：YAG laser deposition （PLD） under influence of laser fluence on ablation rate and deposition rate was discussed. X-ray diffraction （XRD） investigations of the deposited films showed an amorphous structure. The droplet density on the film surface observed by scanning electron microscopy （SEM） analyses was extremely low. It was experimentally proved that the droplets on the film surface originated from liquid phase on the target surface, Profilometric measurements of the deposited Nb films revealed a substantial asymmetry in the film thickness related to the plume deflection effect. The measured electrical resistivity of the Nb film was higher than that of high purity Nb bulk. The present investigations of ablation and deposition process of Nb thin films are related to its potential application in superconducting radio-frequency （SRF） cavities.
