Resonant X-ray scattering (RXS) has become one of the prime techniques to study of charge and
spin order in reciprocal space, owing to its high sensitivity to electronic states near the Fermi energy.
We have applied resonant X-ray methods to explore the emergent organization of the electronic
degrees of freedom into periodically modulated patterns – a hallmark of strongly-correlated quantum
solids. The consequent breaking of translational symmetry is often manifested in the form of
charge- or spin-density-wave, two phenomena which are essential to the physics of two families of
compounds in particular cuprates and nickelates.
On the cuprate front, I will review the latest efforts to broadly chart out charge order across the
extended doping-temperature phase diagram using RXS, as well as discuss recent implementations
to extract symmetry information from the tensorial nature of the resonant scattering process.
On the rare earth nickelates (RENiO3) front, I will focus on some of our recent efforts to use RXS
at high spatial resolutions (50-75 nm) to visualize the nanoscale texture of spin-density-waves
across the Neel and metal-insulator transition. I will discuss the experimental trends observed
both in pristine NdNiO3 thin films and in electron-doped SmNiO3, where control of the oxygen
stoichiometry leads to dramatic changes in the electronic transport.
I will conclude with a few ideas and prospects on the use of coherent soft x-ray scattering methods
(coherent diffractive imaging and ptychography) to map out the texture of electronic orders at even
higher spatial resolutions, and with orders of magnitude improvements in imaging efficiency