Abstract

A charge density wave (CDW) submitted to an electric field displays a strong shear deformation because of pinning at the lateral surfaces of the sample. This CDW transverse pinning was recently observed but has received little attention from a theoretical point of view until now despite important consequences on electrical conductivity properties. Here, we provide a description of this phenomenon by considering a CDW submitted to an external dc electric field and constrained by boundary conditions including both longitudinal pinning due to electrical contacts and transverse surface pinning. A simple formula for the CDW phase is obtained in 3D by using the Green function and image charges method. In addition, an analytical expression of the threshold field dependence on both length and sample cross-section is obtained by considering the phase slip process. We show that the experimental data are well reproduced with this model and that bulk pinning can be neglected. This study shows that the dynamical properties of CDW systems could be mainly driven by boundary effects, despite the comparatively huge sample volumes.

Graphical abstract

中文翻译：

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表面钉扎在提交给外部dc场的电荷密度波动力学中的重要作用

摘要

由于钉扎在样品的侧面，施加到电场的电荷密度波（CDW）显示出很强的剪切变形。最近观察到了这种CDW横向钉扎，但是尽管对电导率性能有重要影响，但从理论上讲至今仍很少受到关注。在这里，我们通过考虑CDW施加到外部dc电场并受边界条件（包括由于电接触引起的纵向钉扎和横向表面钉扎）限制的条件来描述这种现象。通过使用Green函数和图像电荷方法，可以在3D中获得CDW相位的简单公式。此外，通过考虑相位滑移过程，可以获得阈值场与长度和样品横截面的关系的解析表达式。我们表明，使用该模型可以很好地再现实验数据，并且可以忽略批量钉扎。这项研究表明，尽管样本量相对较大，但CDW系统的动力学特性可能主要由边界效应驱动。

图形概要