Browsing by Author "Shapiro, B. Y."

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Experimental Presentation of Microwave Absorption due to Shaking of JV by AC Magnetic Field in Bi2212 and Bi2223
(2009-05-01)
Shaltiel, D.
;
von Nidda, H. -A. Krug
;
Shapiro, B. Y.
;
Rosenstein, B.
;
Loidl, A.
The Josephson Vortex dynamics in high anisotropy superconductors Bi2212 and Bi2223 induced by AC magnetic field collinear to DC magnetic field and parallel to the layers is studied via their interaction with microwave field. Experimental results as function of DC magnetic field, AC magnetic field and temperature are presented. The AC induced microwave dissipation is larger than dissipation without AC field. The results are explained by the theoretical interpretation reported recently due to shaking by the AC field that depins the JV (Shaltiel et al., Phys. Rev. B 77, 014508, 2008). Similar behavior in these two compounds as a function of the variables involved discloses that the shaking effect should be observed in any high anisotropy superconductors. It shows that the AC field interacting with JV has an active and not the usual passive modulating role of the DC field in EPR dissipation experiments. The technique can be used to investigate JV dynamics and JV phase diagram.
Vortex-Antivortex Annihilation and Flux Turbulence in Layered Type-II Superconductors
(2012-04-01)
Dvash, E. E.
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Shapiro, I.
;
Rosenstein, B.
;
Logoboy, N.
;
Shapiro, B. Y.
New mechanism of turbulence instability of standing flux-antiflux front in layered superconductors is presented. We describe two assisting mechanisms destabilizing the standing vortex-antivortex front. There are anisotropy of the layered superconductors and the heat, released by the vortex-antivortex annihilation. We present the conditions of the front stability for various anisotropy and heating parameters. We predict that heat released by the vortex-antivortex annihilations enhances the turbulence instability in superconductors with small anisotropy. The characteristic size of the unstable pattern is estimated. The results are in a good agreement with recent experiments.