Wei Xiaoxiao, Zhu Liang, Wu Ziming, Shi Zhenzhong
School of Physical Science and Technology, Soochow University, Suzhou 215006, People's Republic of China.
Institute for Advanced Study, Soochow University, Suzhou 215006, People's Republic of China.
J Phys Condens Matter. 2024 Sep 5;36(48). doi: 10.1088/1361-648X/ad7438.
Nonlinear transport behavior is one of the signatures of the formation of electronic crystals such as charge density wave (CDW), as it provides evidence for their collective motion. Such experimental evidence has been widely reported in quasi-one-dimensional (1D) materials but is rarely studied in 2D systems. Only a few studies on the RTematerials have been previsouly reported. Here we report for the first time the observation of CDW depinning and sliding in the layered 1-TiSecompound, based on the observation of (1) nonlinear voltage-current characteristics and (2) the electrical noise, which are associated with the CDW depinning and sliding process. Similar measurements are also conducted on quasi-1D system NbSe. The depinning behavior of the CDWs with different dimensionalities in these two systems are compared. It is found that the threshold electric field () increases linearly with decreasing temperature for the 2D case, consistent with previous results on RTe, while it demonstrated an activated behavior in 1D, as expected within the weak-pinning Fukuyama-Lee-Rice framework. Such a distinction of the threshold behavior in CDW systems of different dimensions therefore indicates a possible strong pinning picture in higher-dimensional CDW systems in general.is found to be much higher in 1-TiSe, consistent with a strong pinning picture, and could account for the scarcity of the depinning study in these 2D systems. Our results thus pave the way for a unified understanding of the CDW collective motion in different dimensionalities.
非线性输运行为是诸如电荷密度波（CDW）等电子晶体形成的特征之一，因为它为其集体运动提供了证据。此类实验证据在准一维（1D）材料中已被广泛报道，但在二维系统中却很少被研究。此前仅有少数关于RTe材料的研究报道。在此，我们首次报告了基于以下两点观察结果，在层状1-TiSe化合物中观测到CDW脱钉和滑移现象：（1）非线性电压-电流特性；（2）与CDW脱钉和滑移过程相关的电噪声。我们还对准一维系统NbSe进行了类似测量。比较了这两个系统中不同维度的CDW脱钉行为。结果发现，对于二维情况，阈值电场（）随温度降低呈线性增加，这与先前关于RTe的结果一致，而在一维情况下，它表现出激活行为，这在弱钉扎的Fukuyama-Lee-Rice框架内是预期的。因此，不同维度的CDW系统中阈值行为的这种差异表明，一般来说，在高维CDW系统中可能存在强钉扎情况。在1-TiSe中发现的值要高得多，这与强钉扎情况一致，并且可以解释这些二维系统中脱钉研究较少的原因。我们的结果因此为统一理解不同维度的CDW集体运动铺平了道路。
