Workshop Scope

The subtle interplay of lattice, charge, orbital, and spin degrees of freedom in complex oxides gives rise to rich phase diagrams of competing and coexisting phases characterized by magnetic, electronic and/or orbital order. For example, colossal magnetoresistance can emerge where ferromagnetic and antiferromagnetic domains compete, charge-ordered and superconducting regions are present simultaneously in materials exhibiting high-temperature superconductivity and coexisting conducting and insulating phases with characteristic orbital occupancy can occur near metal-insulator transitions. Additionally, externally applied fields (electric, magnetic, or strain) or other external excitations (light or heat) can tip the energy balance towards one phase or support heterogeneity and phase coexistence and provide the means to perturb and tailor ordered phases at the nanoscale.
Engineering nanomaterials with structural, electronic and magnetic order beyond what is found in bulk materials is possible today through the technique of thin film epitaxy, effectively a method of ‘spray painting’ atoms on single crystalline substrates to create precisely customized layered structures with atomic arrangements defined by the underlying substrate. Charge transfer and spin polarization across interfaces as well as imprinting nanoscale heterogeneity between adjacent layers lead to intriguing and important new ordering phenomena, testing our understanding of basic physics and creating new functionalities. Moreover, abrupt changes in magnetic or electronic order between nanoscale domains can lead to unique phases that are localized at domain walls, including conducting domain walls in insulating ferroelectrics, and ferromagnetic domain walls in antiferromagnets.

Scanning soft x-ray based spectromicroscopy and scattering techniques are powerful tools for probing order and function on the micro- and nanoscale since they provide detailed magnetic and electronic information with element-specificity and sensitivity to the symmetry of the absorber site with down to nanometer spatial resolution. Soft x-ray scattering approaches can selectively probe phases only found near interfaces in multilayers or in domain walls of periodic domain arrays. New soft x-ray scanning microscopy and scattering techniques enabled by the exceptional coherence of ALS-U will enable in-depth understanding of ordered phases, phase co-existence, nanoscale heterogeneity, and unique domain wall characteristics in functional complex oxides. The very high coherent flux provided by ALS-U means that all photons in an x ray beam can be focused into a small spot using diffractive optics like zone plates for scanning microscopy or nano-scattering techniques. Moreover, utilizing the phase of the x-ray beam for coherent diffraction allows projecting material’s heterogeneity into a speckle pattern and monitoring its time dependence, providing important information about the fluctuation dynamics of the systems and/or its response to and external excitation.

In this workshop opportunities and future directions for characterizing ordering phenomena in functional complex oxides using soft x-ray spectromicrocopy and scattering at ALS-U will be featured and discussed.

Target audience: Researchers of any level of experience (student, postdoc, PI) interested in the electronic, orbital, and magnetic characteristics of complex oxides. The organizing team will encourage the participation of students and postdoctoral scholar as presenters and in discussions.

Duration of the workshop: 1-1/2 days