Suppression of geometrical barrier in $B{i}_{2}S{r}_{2}CaC{u}_2{O}_{8+\delta }$ crystals by Josephson vortex stacks

Abstract

Differential magneto-optics are used to study the effect of dc in-plane magnetic field on hysteretic behavior due to geometrical barriers in $B{i}_{2}S{r}_{2}CaC{u}_2{O}_{8+\delta }$ crystals. In absence of in-plane field a vortex dome is visualized in the sample center surrounded by barrier-dominated flux-free regions. With in-plane field, stacks of Josephson vortices form vortex chains which are surprisingly found to protrude out of the dome into the vortex-free regions. The chains are imaged to extend up to the sample edges, thus providing easy channels for vortex entry and for drain of the dome through geometrical barrier, suppressing the magnetic hysteresis. Reduction of the vortex energy due to crossing with Josephson vortices is evaluated to be about two orders of magnitude too small to account for the formation of the protruding chains. We present a model and numerical calculations that qualitatively describe the observed phenomena by taking into account the demagnetization effects in which flux expulsion from the pristine regions results in vortex focusing and in the chain protrusion. Comparative measurements on a sample with narrow etched grooves provide further support to the proposed model.

arXiv comment12 figures (low res.) Higher resolution figures are available at the Phys Rev B version. Typos corrected

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Cited by in corpus (7)

• Optical Manipulation of Single Flux Quanta
• Critical current in thin flat superconductors with Bean-Livingston and geometrical barriers
• Attractive interaction between superconducting vortices in tilted magnetic fields
• Suppression of Geometric Barrier in Type II Superconducting Strips
• Impact of border defects on the magnetic flux penetration in superconducting films
• Lamellar mesophase nucleated by Josephson vortices at the melting of the vortex lattice in $B{i}_{2}S{r}_{2}CaC{u}_2{O}_{8+delta}$
• Pre-melting of crossing vortex lattices