8,062 research outputs found
Realization of Artificial Ice Systems for Magnetic Vortices in a Superconducting MoGe Thin-film with Patterned Nanostructures
We report an anomalous matching effect in MoGe thin films containing pairs of
circular holes arranged in such a way that four of those pairs meet at each
vertex point of a square lattice. A remarkably pronounced fractional matching
was observed in the magnetic field dependences of both the resistance and the
critical current. At the half matching field the critical current can be even
higher than that at zero field. This has never been observed before for
vortices in superconductors with pinning arrays. Numerical simulations within
the nonlinear Ginzburg-Landau theory reveal a square vortex ice configuration
in the ground state at the half matching field and demonstrate similar
characteristic features in the field dependence of the critical current,
confirming the experimental realization of an artificial ice system for
vortices for the first time.Comment: To appear in Phys. Rev. Let
Physical properties of single crystalline BaSn5
We present a comprehensive study of the binary intermetallic superconductor,
BaSn5. High-quality single crystalline BaSn5 was grown out of Sn flux. Detailed
thermodynamic and transport measurements were performed to study BaSn5's normal
and superconducting state properties. This material appears to be a strongly
coupled, multiband superconductor. Hc2(T)is almost isotropic. De Haas-van
Alphen oscillations were observed and two effective masses were estimated from
the FFT spectra. Hydrostatic pressure causes a decrease in the superconducting
transition temperature at the rate of ~ -0.053 K/kbar.Comment: 8 pages and 9 figure
Doping and Irradiation Controlled Vortex Pinning Behavior in BaFe2(As1-xPx)2 Single Crystals
We report on the systematic evolution of vortex pinning behavior in isovalent
doped single crystals of BaFe2(As1-xPx)2. Proceeding from optimal doped to
ovedoped samples, we find a clear transfor- mation of the magnetization
hysteresis from a fishtail behavior to a distinct peak effect followed by a
reversible magnetization and Bean Livingston surface barriers. Strong point
pinning dominates the vortex behavior at low fields whereas weak collective
pinning determines the behavior at higher fields. In addition to doping
effects, we show that particle irradiation by energetic protons can tune vortex
pinning in these materials.Comment: 4 pages, 4 figures,significant change of eraly version, accepted by
PRB rapid communication
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