JAPC - Properties of Complex Oxides at the nanoscale

Speaker: Dr. Amos Sharoni, Department of Physics, University of California, San Diego

Topic: "Properties of Complex Oxides at the nanoscale: First Order Phase Transitions through Avalanches."

Time: 2:00 PM, Friday, December 5th, 2008

Place: P-148 (refreshments will be served at 1:45 PM in P145A)

Abstract: Properties of complex oxides have been fascinating the physical world for decades, including many materials which show a phase transition, among which are high temperature superconductors, multiferroics, and metal insulator transition (MIT) materials. We have studied a member of the later group, vanadium oxide (VO₂), which in spite of been known for decades, keeps surprising researchers today. We find that the MIT of nano-scaled VO₂ devices is drastically different from the smooth transport curves measured on large samples. The temperature driven transition occurs through a series of avalanches ranging over 2 decades in magnitude. We will discuss the surprising distribution of resistance avalanches and their relation with different physical systems. In addition, we show interesting outcomes of the percolative nature of the measurement, what we can learn from it and the connection to the avalanches. Attention will be given to the effect of the VO₂ junction dimensions and of the transport measurement conditions.

This work was supported and funded by the U.S. Department of Energy and the AFOSR.

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