We report the observation of a Skyrmion lattice in the chiral multiferroic insulator Cu2OSeO3 using Cu L3-edge resonant soft x-ray diffraction. We observe the unexpected existence of two distinct Skyrmion sublattices that arise from inequivalent Cu sites with chemically identical coordination numbers but different magnetically active orbitals. The Skyrmion sublattices are rotated with respect to each other, implying a long wavelength modulation of the lattice. The modulation vector is controlled with an applied magnetic field, associating this moirélike phase with a continuous phase transition. Our findings will open up a new class of science involving manipulation of quantum topological states.

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The dynamics of an order parameter's amplitude and phase determines the collective behaviour of novel states emerging in complex materials. Time-and momentum-resolved pump-probe spectroscopy, by virtue of measuring material properties at atomic and electronic time scales out of equilibrium, can decouple entangled degrees of freedom by visualizing their corresponding dynamics in the time domain. Here we combine time-resolved femotosecond optical and resonant X-ray diffraction measurements on charge ordered La 1.75 sr 0.25 nio 4 to reveal unforeseen photoinduced phase fluctuations of the charge order parameter. such fluctuations preserve long-range order without creating topological defects, distinct from thermal phase fluctuations near the critical temperature in equilibrium. Importantly, relaxation of the phase fluctuations is found to be an order of magnitude slower than that of the order parameter's amplitude fluctuations, and thus limits charge order recovery. This new aspect of phase fluctuations provides a more holistic view of the phase's importance in ordering phenomena of quantum matter.

We report the observation of ferromagnetic resonance (FMR) in SrRuO3 using the time-resolved magneto-optical Kerr effect. The FMR oscillations in the time-domain appear in response to a sudden, optically induced change in the direction of easy-axis anisotropy. The high FMR frequency, 250 GHz, and large Gilbert damping parameter, alpha approximately 1, are consistent with strong spin-orbit coupling. We find that the parameters associated with the magnetization dynamics, including alpha, have a nonmonotonic temperature dependence, suggestive of a link to the anomalous Hall effect.