Depinning dynamics of two-dimensional magnetized colloids on a substrate with periodic pinning centers

Y.G. Cao, Z.F. Zhang, M.H. Zhao, G.Y. Fu and D.X. Ouyang

Physica A: Statistical Mechanics and its Applications, 2012, vol. 391, issue 10, 2940-2947

Abstract: We study, by Langevin simulations, the depinning dynamics of two-dimensional magnetized colloids on a substrate with periodic pinning centers. When the number ratios of pinnings to colloids are 1:1 matching and at finite temperature, we find for the first time crossovers from plastic flow through elastic smectic flow to elastic crystal flow near the depinning with increasing the pinning strength. There exists a power-law scaling relationship between the average velocity of colloids and the external driving force for all the three types of flows. It is found that the critical driving force and the power-law scaling exponent as well as the average intensity of Bragg peaks are invariant basically in the region of elastic smectic flow. We also examine the temperature effect and it reveals that the above dynamic moving phases and their transitions could be attributed to the interplay between thermal fluctuation and pinning potential. At sufficiently low temperature, the thermal fluctuation could be neglected and the colloids near the depinning move in the elastic crystal flow no matter what the pinning strength. In addition, the number of pinning centers is changed and when it is close to the number of colloids, there appears a peak in the critical driving force and a dip in the power-law scaling exponent, respectively. The peak and dip are more pronounced for higher pinning strength.

Keywords: Depinning; Magnetized colloid; Plastic flow; Elastic smectic flows; Elastic crystal flow (search for similar items in EconPapers)
Date: 2012
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Persistent link: https://EconPapers.repec.org/RePEc:eee:phsmap:v:391:y:2012:i:10:p:2940-2947

DOI: 10.1016/j.physa.2012.01.020

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