Superconductivity in ultrathin films : from extremely disordered to crystalline films
Jeudi 6 juin 2013 14:00
- Duree : 1 heure
Lieu : Salle "Nevill Mott" D420 - Institut Néel - Building D, CNRS Polygone scientifique, 25 rue des martyrs, 38000 Grenoble
Orateur : Vladimir CERCHEZ (INSP, Paris)
I will present our recent results on the study of the ultrathin superconducting films. In the first part of the talk I will present STM/STS measurements on ultrathin films of niobium nitride (NbN) close to the superconductor-insulator transition (SIT). Analysis of our results shows that in NbN films approaching the SIT, Coulomb interactions are an efficient mechanism to reduce the superconducting gap and the critical temperature. However, the properties of the thinnest films deviate from this scenario, most probably due to the phase fluctuations of the superconducting order parameter. In the second part of the talk, some of our results on the study of lead atomic monolayers on the surface of Si(111) will be presented. Depending on the lead surface coverage the system Pb/Si(111) can pass from a strongly disordered insulator to a bad metal and then for higher Pb coverage to a superconductor. The effects of disorder, eventually enhanced by Coulomb repulsion, and the mesoscopic inhomogeneity on the electronic properties of the Pb film will be presented and discussed.
Contact : pierre.mallet@grenoble.cnrs.fr
Discipline évènement : (Physique)
Entité organisatrice : (Institut Néel / QUEST)
Nature évènement : (Séminaire)
Site de l'évènement : Polygone scientifique
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