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Date/Time:Thursday, 14 Mar 2013 - Thursday, 14 Mar 2013
Location:PHYSICS Hall Room 5
Phone:515-294-5630
Channel:Condensed Matter Physics
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Yuanyuan Tang

Ultra-thin metal films on semiconductor substrates have been a playground for the study of electronic transport properties of low dimensional materials. However, the experimental measurements on the electric transport of such systems are still challenging since they only survive in UHV environments due to high chemical activity. We develop the micro-four-point-probe method integrated with standard low-temperature scanning tunneling microscope(STM), which allows the vibration-proof environments and a broad temperature range (4~300 K) for transport measurements. Taking the Ag/Si(111)-(√3-√3)R30 interface as the prototype of two-dimensional metals, the metal-insulator transition is studied. The surface structure characterizations show hexagonal patterns at room temperature, which supports the model of inequivalent triangle structure. A metal-insulator transition occurs at ~115 K. The low temperature transport measurements clearly reveal the strong localization characteristics of the insulating phase.