Special CPM Seminar

How nonlinearity distorts the evidence for photoinduced superconductivity

J. Steven Dodge

Department of Physics
Simon Fraser University

Over a decade of research has suggested that some metallic compounds can be transformed into superconductors by illuminating them with intense beams of laser light. Recently, we have shown that the experimental evidence for this effect could literally be an optical illusion produced by the high-intensity laser illumination. By examining several influential results on photoinduced superconductivity in K₃C₆₀, we have identified a fundamental flaw in their analysis that exaggerates the apparent photoinduced changes to the conductivity. When we account for this error, we find evidence that photoexcitation produces a moderate enhancement of the conductivity, but that there is no need to appeal to a photoinduced phase transition to a superconducting state. Subsequent work on K₃C₆₀ has provided quantitative support for our analysis. After discussing our reanalysis of experiments on K₃C₆₀, I will describe how this error also distorts the evidence for photoinduced superconductivity in the normal state of cuprate superconductors and in the charge-transfer salt BEDT-TTF. Finally, I will discuss how our reinterpretation raises new and interesting questions about the interaction of light with matter.