arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1408.0291cond-mat.supr-concond-mat.soft
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共形晶体和梯度钉扎阵列中涡旋的钉扎、有序和动力学

Pinning, Ordering, and Dynamics of Vortices in Conformal Crystal and Gradient Pinning Arrays

D. Ray, C. Reichhardt, C. J. Olson Reichhardt

摘要:

我们数值研究的磁化,钉扎,订购,和动力学的涡旋相互作用钉扎安排有密度梯度。我们专注于共形晶体结构,通过共形变换空间均匀的周期阵列,以及非共形梯度结构和准周期秩序的结构。共形结构具有密度梯度和局部有序性。使用磁化模拟,我们发现,共形钉扎阵列表现出增强钉扎相比,非共形梯度阵列,以及相比,随机,周期性和准周期性阵列,为广泛的领域。共形阵列的有效性来自于通过共形变换引入阵列的连续长度尺度,允许宽范围的局部衰减效应。在较高的涡填充以上的保形有效性的范围内,我们表明,一个非保形的矩形梯度阵列表现出强烈的钉扎由于一种新的双折射效应和涡序。使用输运模拟,其中涡流被驱动沿梯度,并在一个角度的梯度,我们确认共形钉扎在增加临界电流的有效性。对于旋转驱动器,梯度阵列在垂直于梯度的方向上产生强烈的涡流引导效果。

英文摘要:

We numerically investigate magnetization, pinning, ordering, and dynamics of vortices interacting with pinning arrangements which have a density gradient. We focus on conformal crystal structures obtained by conformally transforming a spatially uniform periodic array, as well as non-conformal gradient structures and structures with quasiperiodic order. The conformal structures feature a density gradient and local ordering. Using magnetization simulations we find that conformal pinning arrays exhibit enhanced pinning compared to non-conformal gradient arrays as well as compared to random, periodic, and quasiperiodic arrays, for a broad range of fields. The effectiveness of conformal arrays arises from the continuum of length scales introduced into the arrays by the conformal transformation, allowing for a broad range of local commensuration effects. At higher vortex fillings above the range of conformal effectiveness, we show that a non-conformal rectangular gradient array exhibits strong pinning due to a novel commensuration effect and vortex ordering. Using transport simulations where vortices are driven along the gradient and at an angle to the gradient, we confirm the effectiveness of conformal pinning at increasing the critical current. For a rotated drive, the gradient arrays produce a strong vortex guidance effect in the direction perpendicular to the gradient.

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