School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, People's Republic of China.
J Phys Condens Matter. 2010 Apr 21;22(15):155101. doi: 10.1088/0953-8984/22/15/155101. Epub 2010 Mar 9.
We perform Langevin simulations on the depinning dynamics of two-dimensional magnetized colloids on a random substrate. On increasing the magnetic field strength, we find for the first time a crossover from plastic to smectic flows as well as a crossover from smectic to elastic crystal flows above depinning. For both the smectic and elastic crystal flows, a power-law scaling relationship could be obtained between the average velocity and applied driving force. The scaling exponent is found to be larger than 1 for smectic flow. But, for the elastic crystal flow, the scaling exponent is found to be less than 1. For the plastic flow, no power-law scaling relationship between the average velocity and applied driving force can be derived and history dependence of the depinning occurs. Within the crossover from plastic to smectic flows, a sudden decrease in the critical driving force is observed, and a sudden increase is found in the critical driving force across the crossover from smectic to elastic crystal flows, accompanied by a crossing of the curves of average velocity versus driving force.
我们对二维各向异性胶体在随机基底上的脱钉动力学进行了朗之万模拟。随着磁场强度的增加，我们首次发现了从塑性流动到近晶相流动以及从近晶相流动到弹性晶体流动的交叉。对于近晶相和弹性晶体流动，都可以得到平均速度与驱动力之间的幂律标度关系。发现近晶相流动的标度指数大于 1，而对于弹性晶体流动，标度指数小于 1。对于塑性流动，不能得到平均速度与驱动力之间的幂律标度关系，并且存在脱钉的历史依赖性。在从塑性到近晶相流动的交叉处，观察到临界驱动力的突然下降，并且在从近晶相到弹性晶体流动的交叉处发现临界驱动力的突然增加，伴随着平均速度与驱动力的曲线的交叉。
