Browsing by Author "Lien, An-Shao"

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Long electron dephasing length and disorder-induced spin-orbit coupling in indium tin oxide nanowires
(2010-11-15)
Hsu, Yao-Wen
;
Chiu, Shao-Pin
;
Lien, An-Shao
;
Lin, Juhn-Jong
;
電子物理學系
We have measured the quantum-interference magnetoresistances in two single indium tin oxide (ITO) nanowires between 0.25 and 40 K, by using the four-probe configuration method. The magnetoresistances are compared with the one-dimensional weak-(anti)localization theory to extract the electron dephasing length L-phi. We found, in a 60-nm-diameter nanowire with a low resistivity of rho(10 K) =185 mu Omega cm, that L-phi is long, increasing from 150 nm at 40 K to 520 nm at 0.25 K. Therefore, the nanowire reveals strict one-dimensional weak-localization effect up to several tens of degrees of kelvin. In a second 72-nm-diameter nanowire with a high resistivity of rho(10 K)=1030 mu Omega cm, the dephasing length is suppressed to L-phi(0.26 K)=200 nm, and thus a crossover of the effective device dimensionality from one to three occurs at about 12 K. In particular, disorder-induced spin-orbit coupling is evident in the latter sample, manifesting weak-antilocalization effect at temperatures below similar to 4 K. These observations demonstrate that versatile quantum-interference effects can be realized in ITO nanowires by controlling differing levels of atomic defects and impurities.
Long electron dephasing length and disorder-induced spin-orbit coupling in indium tin oxide nanowires
(2010-11-15)
Hsu, Yao-Wen
;
Chiu, Shao-Pin
;
Lien, An-Shao
;
Lin, Juhn-Jong
;
電子物理學系
We have measured the quantum-interference magnetoresistances in two single indium tin oxide (ITO) nanowires between 0.25 and 40 K, by using the four-probe configuration method. The magnetoresistances are compared with the one-dimensional weak-(anti)localization theory to extract the electron dephasing length L(phi). We found, in a 60-nm-diameter nanowire with a low resistivity of rho(10 K) =185 mu Omega cm, that L(phi) is long, increasing from 150 nm at 40 K to 520 nm at 0.25 K. Therefore, the nanowire reveals strict one-dimensional weak-localization effect up to several tens of degrees of kelvin. In a second 72-nm-diameter nanowire with a high resistivity of rho(10 K)=1030 mu Omega cm, the dephasing length is suppressed to L(phi)(0.26 K)=200 nm, and thus a crossover of the effective device dimensionality from one to three occurs at about 12 K. In particular, disorder-induced spin-orbit coupling is evident in the latter sample, manifesting weak-antilocalization effect at temperatures below similar to 4 K. These observations demonstrate that versatile quantum-interference effects can be realized in ITO nanowires by controlling differing levels of atomic defects and impurities.
Temporal universal conductance fluctuations in RuO(2) nanowires due to mobile defects
(2011-10-17)
Lien, An-Shao
;
Wang, L. Y.
;
Chu, C. S.
;
Lin, Juhn-Jong
;
電子物理學系
Temporal universal conductance fluctuations (TUCF's) are observed in RuO(2) nanowires at cryogenic temperatures. The fluctuations persist up to very high T similar to 10 K. Their root-mean-square magnitudes increase with decreasing T, reaching similar to 0.2e(2)/h at T less than or similar to 2 K. These fluctuations are shown to originate from scattering of conduction electrons with rich amounts of mobile defects in artificially synthesized metal oxide nanowires. TUCF characteristics in both one-dimensional saturated and unsaturated regimes are identified and explained in terms of current theories. Furthermore, the TUCF's as a probe for the characteristic time scales of the mobile defects (two-level systems) are discussed.
Temporal universal conductance fluctuations in RuO2 nanowires due to mobile defects
(2011-10-17)
Lien, An-Shao
;
Wang, L. Y.
;
Chu, C. S.
;
Lin, Juhn-Jong
;
電子物理學系
Temporal universal conductance fluctuations (TUCF's) are observed in RuO2 nanowires at cryogenic temperatures. The fluctuations persist up to very high T similar to 10 K. Their root-mean-square magnitudes increase with decreasing T, reaching similar to 0.2e(2)/h at T less than or similar to 2 K. These fluctuations are shown to originate from scattering of conduction electrons with rich amounts of mobile defects in artificially synthesized metal oxide nanowires. TUCF characteristics in both one-dimensional saturated and unsaturated regimes are identified and explained in terms of current theories. Furthermore, the TUCF's as a probe for the characteristic time scales of the mobile defects (two-level systems) are discussed.