title: Pseudoisotropic upper critical field in cobalt-doped SrFe2As2 epitaxial films.
abstract: We present resistivity measurements of the complete superconducting upper critical field (H{c2}) phase diagram as a function of angle (theta) and temperature (T) for cobalt-doped SrFe2As2 epitaxial films to 0.5 K and 50 T. Although H{c2}(theta) at 10 K is indistinguishable from that derived from a single-band anisotropy model, the apparent anisotropy H{c2}{ perpendicularc}/H{c2};{ parallelc} linearly decreases to 1 at low T, with H{c2}(0)=47 T. The data are well described by a two-band model with small, opposing anisotropies for the bands. This unusual relationship is confirmed by the observation of a local maximum for H{c2};{ parallelc} at low T.
authors.affiliation: National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. sbaily@lanl.gov
authors.forename: S A
authors.initials: SA
authors.lastname: Baily
authors.forename: Y
authors.initials: Y
authors.lastname: Kohama
authors.forename: H
authors.initials: H
authors.lastname: Hiramatsu
authors.forename: B
authors.initials: B
authors.lastname: Maiorov
authors.forename: F F
authors.initials: FF
authors.lastname: Balakirev
authors.forename: M
authors.initials: M
authors.lastname: Hirano
authors.forename: H
authors.initials: H
authors.lastname: Hosono