This book makes significant strides in imaging, engineering, and understanding antiferromagnetic textures in complex quantum materials. Developing advanced resonant coherent soft X-ray scattering (RCSXS), the author discusses how nanoscale magnetic textures evolve to reveal inter-relation with other orders, with specific application to rare earth nickelates and iron intercalated niobium di-sulfide. With clarity and rigor, this thesis describes pioneering use of RCSXS to probe metastable states, offering a pedagogical introduction complete with simulations and analysis tools. The dissertation also introduces a practical helium ion implantation method to engineer lateral electronic heterogeneitythoroughly characterized and contextualized as a benchmark for metastable phase manipulation. The writing combines the scientific depth of nickelate physics with the elegance of the fabrication technique, guiding the reader through complex phenomena finally utilizing RCSXS to observe the antiferromagnetic texture fabricated. A particular methodological advance is the introduction of a multi-beam-spot RCSXS technique to probe long length-scale kinetic and dynamic electronic texturespushing the boundaries to think beyond the conventional resonant coherent scattering methods. Through extensive designs and simulations, the author proposes modifications to X-ray optics used in resonant coherent soft X-ray scattering to observe phenomena related to driven quantum metastable phases.
