| Autor: |
U. Murek, R. Schäfer, C. Braden, Klaus Hecker, W. Langheinrich, Helmut Hegger |
| Rok vydání: |
1994 |
| Předmět: |
|
| Zdroj: |
Physical review. B, Condensed matter. 50(24) |
| ISSN: |
0163-1829 |
| Popis: |
Magnetoconductance experiments on metallic nanobridges were performed in a mesoscopic two-probe configuration. In our samples a short wire of length L=100 nm to L=1 \ensuremath{\mu}m and cross section 30\ifmmode\times\else\texttimes\fi{}30 ${\mathrm{nm}}^{2}$ connected two funnel-shaped contacts. The contacts served as both voltage and current leads. The dependence of conductance fluctuations (CF's) on the length of the mesoscopic wires was measured at temperatures T\ensuremath{\le}100 mK. In this temperature range the rms amplitude \ensuremath{\delta}G of the CF equals its low-temperature value for all investigated devices. Magnetoconductance fluctuations are caused by the interference of electrons within a phase coherent area ${\mathit{F}}_{\mathit{c}\mathit{p}\mathit{h}\mathit{i}}$. In short bridges ${\mathit{F}}_{\mathit{c}\mathit{p}\mathit{h}\mathit{i}}$ encloses the nm wire and parts of the funnel-shaped contacts. Quantum diffusion of conduction electrons into the contacts leads to high-frequency magneto-CF. The diffusion in the wide contact regions become more and more important with decreasing wire length. This results in a decreasing correlation field ${\mathit{B}}_{\mathit{c}}$ with decreasing wire length. We observed a weak dependence of the rms amplitude \ensuremath{\delta}G of the CF on the wire length, which we attribute to a dimensional crossover from a one-dimensional (1D) to a 2D system. Besides the saturation value of \ensuremath{\delta}G we studied the temperature dpeendence of CF's in the range 280 mK to 10 K for a L=200 nm wire. The decrease of the magnitude of the CF starts only at Tg500 mK. For higher temperatures it follows a ${\mathit{T}}^{\mathrm{\ensuremath{-}}1/2}$ law. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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