Universal Conductance Fluctuations in Single-crystalline RuO2 Nanowires

• Main Authors: Lien, An-Shao, 連安劭
• Other Authors: Lin, John-Jong
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/21445977922551322950

碩士 === 國立交通大學 === 物理研究所 === 97 === Recently, as progresses in computer instustry, the electronic devices are made smaller and smaller. In such small systems, classical Boltzmann transport theorem is not applied and quantum modification must be added. As a result, quantum interference phenomena have been important topics in physics. The weak localization effect has been studied for a long time and has become a convenient tool to determine the dephasing time. On the other hand, there are less articles about universal conductance fluctuations, which has been pointed out having great potential for researches. Due to its sensitivity to mobile impurities, direct observations to atomic or even subatomic movements of impurities is possible and can be applied in many fields. Using the e-beam lithography process to make four-porbe contacts, we measured the electric properties of individual single-crystalline RuO2 nanowires at low temperature. We observed increasing conductance fluctuations as temperature decreased, which has been thought as a feature of universal conductance fluctuations. By analysis, the UCF should come from a one dimension system. But with thermal averaging effect, the data can’t be fit very well. We didn’t observe the reduction of fluctuation magnitude in the present of magnetic field. In R-T data, the increasing resistivity at low temperature was much more larger than the contribution of weak localization effect and electron-electron interaction, and maybe caused by two-level system Kondo effect. We suppose that the universal conductance fluctuations are due to the two-level systems formed by point defects in nanowires. Results of R-T data also support this argument.