Filamentary flow of vortices in a Bi2Sr2Ca1Cu2O8+delta single crystal

Article

关键词: CHARGE-DENSITY WAVES;    VORTEX-LATTICE;    PHASE-DIAGRAM;    FLUX LATTICES;    LINE;    DYNAMICS;    DRIVEN;    TRANSITION;    NEUTRON;    METASTABILITY;   

DOI  :  10.1103/PhysRevB.81.094521

来源: SCIE

【 摘 要 】

Using microbridge technique, we have studied the vortex dynamics in a very low-temperature region (i.e., T/T-c --> 0) of the B-T phase diagram of Bi2Sr2Ca1Cu2O8+delta single crystal. We distinguish two types of vortex dynamics near the depinning threshold depending on the magnitude of the vortex-vortex interactions. For 0.01 < mu H-0<1 T, we show that current-voltage (I-V) characteristics are strongly dependent on the history of magnetic field and current cycling. The sharp peak, so-called peak effect, observed in mu H-0-I-c curve is due to a metastable state that can be removed after current cycling. At low field, I-V curves show steps that would be clearly related to fingerprint phenomenon since the relationship R-d=dV/dI exists. This can be attributed to vortices flow through uncorrelated channels for the highly defective lattice. Indeed, as field sufficiently increases, these peaks merge to make broader ones indicating a crossover from filamentary strings to braid riverlike in which vortex-vortex interactions becomes significant. As confirmed by the discontinuity in the critical exponent value beta determined in the vicinity of the threshold current using the power-law scaling V similar to(I-I-c)(beta) with a crossover from beta=2.2 to beta=1.2. The strong vortex correlation along the c axis has been clearly demonstrated using the dc-flux-transformer geometry for transport measurements that confirms the pseudo-two-dimensional (2D) behavior of the flux-line lattice. Our transport studies are in good agreement with simulations results of 2D elastic objects driven by repulsive interactions through a random pinning potential.

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