Spontaneous fluctuations in quantum materials probed by coherent x-rays

Speaker: Lingjia Shen, Lund University 

Program Description:

Spontaneous fluctuations describe the noise of a state induced by thermodynamics, Heisenberg’s uncertainty principle, or both. Some of the most intricate phenomena in fundamental physics are driven by these spontaneous fluctuations. In a variety of electronic devices, spontaneous fluctuations also determine the intrinsic limit of their operational stability. As a result, experimental detection and characterization of this noise is of great importance. In this talk, I will demonstrate the use of coherent x-rays generated by both synchrotron radiation and free-electron lasers to probe the different types of spontaneous fluctuations in the high-temperature superconductor La2-xSrxCuO4 and magnetic skyrmion superlattice Fe/Gd. These fluctuations have a time span over 18 orders of magnitude.