title: Microwave-stimulated superconductivity due to presence of vortices.
abstract: The response of superconducting devices to electromagnetic radiation is a core concept implemented in diverse applications, ranging from the currently used voltage standard to single photon detectors in astronomy. Suprisingly, a sufficiently high power subgap radiation may stimulate superconductivity itself. The possibility of stimulating type II superconductors, in which the radiation may interact also with vortex cores, remains however unclear. Here we report on superconductivity enhanced by GHz radiation in type II superconducting Pb films in the presence of vortices. The stimulation effect is more clearly observed in the upper critical field and less pronounced in the critical temperature. The magnetic field dependence of the vortex related microwave losses in a film with periodic pinning reveals a reduced dissipation of mobile vortices in the stimulated regime due to a reduction of the core size. Results of numerical simulations support the validy of this conclusion. Our findings may have intriguing connections with holographic superconductors in which the possibility of stimulation is under current debate.
authors.affiliation: Dpto. Física Materia Condensada C03, Instituto Nicolas Cabrera (INC), Condensed Matter Physics Institute (IFIMAC), Universidad Autoenoma de Madrid, 28049, Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Lara
authors.affiliation: Dpto. Física Materia Condensada C03, Instituto Nicolas Cabrera (INC), Condensed Matter Physics Institute (IFIMAC), Universidad Autoenoma de Madrid, 28049, Madrid, Spain.
authors.forename: Farkhad G
authors.initials: FG
authors.lastname: Aliev
authors.affiliation: INPAC- Katholieke Universiteit Leuven, Celestijnenlaan 200D, B3001, Leuven, Belgium and Departement de Physique, Université de Liège, B-4000 Sart Tilman, Belgium.
authors.forename: Alejandro V
authors.initials: AV
authors.lastname: Silhanek
authors.affiliation: INPAC- Katholieke Universiteit Leuven, Celestijnenlaan 200D, B3001, Leuven, Belgium.
authors.forename: Victor V
authors.initials: VV
authors.lastname: Moshchalkov