Correlation time for step structural fluctuations

Bondarchuk, O. ; Dougherty, D. B. ; Degawa, M. ; Williams, E. D. ; Constantin, M. ; Dasgupta, C. ; Das Sarma, S. (2005) Correlation time for step structural fluctuations Physical Review B: Condensed Matter and Materials Physics, 71 (4). 045426_1-045426_10. ISSN 1098-0121

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Time-dependent scanning tunneling microscopy has been used to evaluate step fluctuations as a function of temperature (300-450 K) on Ag(111) films grown on mica. The temporal correlation function scales as a power law in time t1/n with measured values of 1/n varying over a range of 0.19± 0.04 to 0.29±0.04 with no correlation on temperature. The average value of 1/n=0.24±0.01 is consistent with step-edge diffusion limited fluctuations (n=z=4, conserved noise). The magnitude of the time correlation function and the width of the fluctuations both scale with temperature with the same apparent activation energy of Eeff=0.21±0.02 eV, indicating that the correlation time is at most weakly temperature dependent. Direct analysis of the autocorrelation function confirms that the correlation time is at most weakly temperature dependent, and thus the apparent correlation length is strongly temperature dependent. This behavior can be reproduced by assuming that the apparent correlation length is governed by the longest wavelength of step fluctuations that can be sampled in the measurement time interval. Evaluation of the correlation time for previous measurements for Al/Si(111) (z=2) yields the same conclusion about measurement time interval. In both cases the ratio of the measurement time to the effective correlation time is on the order of 10.

Item Type:Article
Source:Copyright of this article belongs to The American Physical Society.
ID Code:83257
Deposited On:17 Feb 2012 04:12
Last Modified:17 Feb 2012 04:12

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