title: A route for a strong increase of critical current in nanostrained iron-based superconductors.
abstract: The critical temperature Tcand the critical current density Jcdetermine the limits to large-scale superconductor applications. Superconductivity emerges at Tc. The practical current-carrying capability, measured by Jc, is the ability of defects in superconductors to pin the magnetic vortices, and that may reduce Tc. Simultaneous increase of Tcand Jcin superconductors is desirable but very difficult to realize. Here we demonstrate a route to raise both Tcand Jctogether in iron-based superconductors. By using low-energy proton irradiation, we create cascade defects in FeSe0.5Te0.5films. Tcis enhanced due to the nanoscale compressive strain and proximity effect, whereas Jcis doubled under zero field at 4.2 K through strong vortex pinning by the cascade defects and surrounding nanoscale strain. At 12 K and above 15 T, one order of magnitude of Jcenhancement is achieved in both parallel and perpendicular magnetic fields to the film surface.
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.|Department of Nanotechnology for Sustainable Energy, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Ozaki
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Lijun
authors.initials: L
authors.lastname: Wu
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhang
authors.affiliation: National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, USA.
authors.forename: Jan
authors.initials: J
authors.lastname: Jaroszynski
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Weidong
authors.initials: W
authors.lastname: Si
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Yimei
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li