RESUMEN
Uniaxial systems often form labyrinthine domains that exhibit short-range order but are macroscopically isotropic and would not be expected to exhibit precise symmetries. However, their underlying frustration results in a multitude of metastable configurations of comparable energy, and driving such a system externally might lead to pattern formation. We find that soft x-ray speckle diffraction patterns of the labyrinthine domains in CoPd/IrMn heterostructures reveal a diverse array of hidden rotational symmetries about the magnetization axis, thereby suggesting an unusual form of emergent order in an otherwise disordered system. These symmetries depend on applied magnetic field, magnetization history, and scattering wave vector. Maps of rotational symmetry exhibit intriguing structures that can be controlled by manipulating the applied magnetic field in concert with the exchange bias condition.
RESUMEN
We report the first proof-of-principle experiment of iterative phase retrieval from magnetic x-ray diffraction. By using the resonant x-ray excitation process and coherent x-ray scattering, we show that linearly polarized soft x rays can be used to image both the amplitude and the phase of magnetic domain structures. We recovered the magnetic structure of an amorphous terbium-cobalt thin film with a spatial resolution of about 75 nm at the Co L3 edge at 778 eV. In comparison with soft x-ray microscopy images recorded with Fresnel zone plate optics at better than 25 nm spatial resolution, we find qualitative agreement in the observed magnetic structure.