The importance of disorder in physics is only matched by the difficulty to study it. For example, the remarkable properties of high-temperature superconductors are greatly affected by variations in the chemical composition of the solid. Techniques that enable measurements of such disorder and its impact on the electronic properties, such as scanning tunnelling microscopy, work only at very low temperatures, and are blind to these physics near the transition temperature. Now, a team of researchers of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Germany and Brookhaven National Laboratory in the United States has demonstrated a new way to study disorder in superconductors using terahertz pulses of light. Adapting methods used in nuclear magnetic resonance to terahertz spectroscopy, the team was able to follow the evolution of disorder in the transport properties up to the superconducting transition temperature for the first time. The work by the Cavalleri group has appeared in Nature Physics.
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