Browsing by Author "Zhang, Yu-Jie"

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Electron dephasing in homogeneous and inhomogeneous indium tin oxide thin films
(2012-03-05)
Wu, Chih-Yuan
;
Lin, Bo-Tsung
;
Zhang, Yu-Jie
;
Li, Zhi-Qing
;
Lin, Juhn-Jong
The electron dephasing processes in two-dimensional homogeneous and inhomogeneous indium tin oxide thin films have been investigated in a wide temperature range 0.3-90 K. We found that the small-energy-transfer electron-electron (e-e) scattering process dominated the dephasing from a few kelvins to several tens of kelvins. At higher temperatures, a crossover to the large-energy-transfer e-e scattering process was observed. Below about 1 to 2 K, the dephasing time tau(phi) revealed a very weak temperature dependence, which intriguingly scaled approximately with the inverse of the electron diffusion constant D, i.e., tau(phi)(T approximate to 0.3 K) proportional to 1/D. Theoretical implications of our results are discussed. The reason why the electron-phonon relaxation rate is negligibly weak in this low-carrier-concentration material is presented.
Logarithmic temperature dependence of Hall transport in granular metals
(2011-08-12)
Zhang, Yu-Jie
;
Li, Zhi-Qing
;
Lin, Juhn-Jong
;
電子物理學系
;
物理研究所
We have measured the Hall coefficient R-H and the electrical conductivity sigma of a series of ultrathin indium-tin-oxide films between 2 and 300 K. A robust R-H proportional to ln T law is observed in a considerably wide temperature range of 2 and similar to 120 K. This ln T dependence is explained as originating from the electron-electron interaction effect in the presence of granularity as theoretically predicted. Furthermore, we observed sigma proportional to ln T law from 3 K up to several tens K, which also arose from the Coulomb interaction effect in inhomogeneous systems. These results provide strong experimental support for the current theoretical concepts for charge transport in granular metals with intergrain tunneling conductivity g(T) >> 1.