  X-ray photon correlation spectroscopy (XPCS) enables us to study dynamics of
antiferromagnets. Using coherent soft X-ray diffraction, we resonantly probe Mn
and Co Bragg peaks in the frustrated magnetic chain compound Lu2CoMnO6
significantly below the Neel temperature. Bragg peaks of incommensurate order
slide towards commensurate 'up up down down' order with decreasing temperature.
Antiferromagnetic inhomogeneities produce speckle within the Bragg peaks, whose
dynamics are probed by XPCS and compared to the classic Axial Next-Nearest
Neighbor Interaction model of frustration. The data supports a novel model
prediction: with decreasing temperature the dynamics become faster.
