Bi_2Sr_2Ca_1Cu_2 O_{8+δ}单晶中无限倾斜模量涡旋的丝状流动
Filamentary flow of vortices with infinite tilt modulus in Bi_2Sr_2Ca_1Cu_2O_{8+δ} single crystal
摘要：
本文用微桥技术研究了Bi_2Sr_2Ca_1Cu_2 O_{8+δ}单晶B-T相图中很低温度区（即T/Tc -> 0）的涡旋动力学。我们区分两种类型的涡动力学附近的脱钉阈值取决于涡涡相互作用的大小。在0.01 <= μ_0H <= 1 T的情况下，电流-电压特性（I-V）强烈地依赖于磁场和电流循环的历史。在μ_0 H-Ic曲线上观察到的尖峰效应（PE）是由一个亚稳态引起的，该亚稳态在电流循环后可以消除。在低场下，I-V曲线表现出明显地引起“指纹现象”的台阶，因为可以看到差分电阻Rd = dV/dI的电流依赖性。我们将其与通过高度缺陷晶格的不相关通道的涡流相关联。事实上，随着场的充分增加，这些峰合并，给出更宽的峰，表明从平行弦到辫状河的交叉，其中涡-涡相互作用变得很重要。正如临界指数值β的不连续性所证实的那样，临界指数值β是在阈值电流附近使用幂律标度V（I-Ic）^β确定的，交叉点从β= 2.2到β= 1.2。沿c轴的强涡旋相关性已清楚地表明，使用直流通量-Transformer几何形状的运输测量，这证实了伪二维行为的FLL。我们的输运研究与最近的模拟结果一致，通过一个随机钉扎势的排斥相互作用驱动的二维弹性物体。
英文摘要：
Using micro-bridge technique, we have studied the vortex dynamics in a very low temperature region (i.e. T/Tc -> 0) of the B-T phase diagram of Bi_2Sr_2Ca_1Cu_2O_{8+δ} 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 <= μ_0H <= 1T, we show that current-voltage characteristics (I-V) are strongly dependent on the history of magnetic field and current cycling. The sharp peak, so called "peak effect" (PE), observed in μ_0H-Ic curve is due to a metastable state which can be removed after current cycling. At low field, I-V curves exhibit steps which clearly enligth a "fingerprint phenomenon" as it can be seen the current dependence of the differential resistance Rd = dV/dI. We associate this to vortices flow through uncorrelated channels for the highly defective lattice. Indeed, as field sufficiently increase, these peaks merge giving broader ones indicating a crossover from filamentaty strings to braid river like in which vortex-vortex interactions becomes significant. As confirmed by the discontinuity in the critical exponent value βdetermined in the vicinity of the threshold current using the power-law scaling V (I-Ic)^βwith a crossover from β= 2.2 to β= 1.2. The strong vortex correlation along the c-axis has been clearly demonstrated using the dc-flux-transformer geometry for transport measurements which confirms the pseudo-2D behaviour of the FLL. Our transport studies are in good agreement with recent simulations results of 2D elastic objects driven by repulsive interactions through a random pinning potential.
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