New opportunities at the Advanced Photon Source: using intermediate-energy x-rays to investigate collective behavior in emergent materials

In an effort to address one of the grand challenges for condensed matter physics in the 21st century, namely to gain an understanding of the physics of materials which exhibit collective electronic phenomena, the Advanced Photon Source at Argonne National Laboratory has developed a new intermediate-energy x-ray (IEX) beamline. Collective behavior of orbital, charge or spin degrees of freedom is at the heart of the complex phase diagram of strongly correlated materials. The investigation of such phenomena requires a full characterization of their ground states and elementary excitations, including unconventional electronic/orbital/magnetic order and electronic band structure.
To this aim, the beamline was designed to serve two distinct but complementary techniques: angle resolved photoemission spectroscopy (ARPES) and resonant soft x-ray scattering (RSXS). ARPES and RSXS are two quintessential probes of the electronic structure in materials and are particularly well suited for investigating collective excitations in strongly correlated electron systems. In this presentation, we will showcase recent science highlights from the beamline in a variety of materials such as superconductors, heavy fermions, complex oxides and neuromorphics. Those demonstrate the unique capabilities of the beamline including polarization control, high energy reproducibility, low harmonic contamination, the highest possible flux and stability in both energy and position across the entire intermediate energy range covering resonances of interest, namely 250-3000 eV.