Collective Dynamics and Slow Relaxation of Charge/Spin Density Wave domains in Antiferromagnetic Chromium

We present coherent x-ray diffraction and x-ray microscopy measurements of slow fluctuations and relaxation of charge- and spin-density wave domains in antiferromagnetic Chromium. Intensity fluctuations of the coherent x-ray speckle of incomensurate charge density wave satellite, combined with time-resolved x-ray microscopy measurements, reveal the collective nature of the uncharacteristically slow domain wall and phase defect fluctuation as well as non-equilibrium charge- and spin-density wavevector relaxation. The observed dynamics of pinned charge- and spin-density wave condensate in Chromium is similar to other examples of elastic media in presence of quenched disorder, ranging from dynamics of vortex lattices in disordered superconductors and sliding friction to snow avalanches and earthquakes. A particularly interesting analogy is dynamics of soft matter undergoing jamming transition, which show similar compressed exponential relaxation behavior.