Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 7: Superconductivity & Solids At Low Temperature - Poster Session

TT 7.60: Poster

Montag, 27. März 2006, 14:00–17:45, P1

Enhancement of the vortex pinning in superconducting MgB₂ films — •Anatolie Sidorenko^1,2,3, Vladimir Zdravkov^1,2, Christian Leierer², Andreas Heinrich², Siegfried Horn², Reinhard Tidecks², Achim Wixforth², Thomas Koch^3,4, and Thomas Schimmel^3,4 — ¹IAP, LISES, ASM, Kishinev, Moldova — ²IP, Universität Augsburg, Germany — ³AP, Universität Karlsruhe, Germany — ⁴INT, Forschungszentrum Karlsruhe, Germany

Superconducting MgB₂ films have extremely high critical current density, up to j_c ∼ 10⁷/cm² at 15 K in zero magnetic field what makes this novel superconductor very attractive for technical applications. But magnesium diboride exhibits a rapid loss of the current carrying capabilities in strong magnetic fields, caused by thermomagnetic instabilities leading to a rapid decrease of the activation energy for magnetic flux motion for U₀(B) in fields of B > 1 Tesla. There are two possible ways to solve the problem of the too low pinning force for high magnetic fields: a) by covering the MgB₂ film with an electronicly isolated highly thermoconducting metallic layer to prevent thermomagnetic instabilities; b) by embedding artificial pinning centers within the film to increase the pinning force and thus the activation barrier for thermally activated flux flow. In the present work we report about the results of our experiments where we used both ways: a) coating of the MgB₂ film with Cu-layers (0.3 µ m − 1.0 µ m thick) for thermo stabilization; b) the adsorption of ferromagnet nanoparticles (10nm - 50nm Fe and Ni particles) on the surface of the MgB₂ film.