Lattice instabilities and emergent collective phases and behavior rooted in the quantum world
PI: Valeri Petkov, Department of Physics, Central Michigan University
The remarkable properties of quantum materials result from strong interactions among their electronic, lattice and spin degrees of freedom and the rich variety of ordered electronic phases that emerge as a consequence, often in a close proximity to each other. If understood and controlled at atomic level, their properties could revolutionize virtually every aspect of science and technology. A fundamental feature of many quantum materials is the locally broken crystal symmetry and presence of lattice distortions due to lattice instabilities. The properties of such materials are difficult to understand because local lattice distortions are difficult to assess using traditional crystallographic techniques.
This project aims to advance through fundamental research the atomic-level understanding of collective electronic phases and behavior emerging in quantum materials exhibiting local lattice distortions. Our hypothesis is that, in many quantum materials, lattice distortions are not induced by changes in the electronic structure but appear as an independent degree of freedom that bridges electronic phases the materials may exhibit. To verify the hypothesis, we will employ resonant total x-ray scattering coupled to atomic pair distribution function analysis and large-scale 3D modeling to study the interaction between lattice distortions, electronic and magnetic degrees of freedom in charge density wave and Mott insulating systems exhibiting competing superconducting, electronic and magnetic orders. Since emergent phenomena are very sensitive to external stimuli, we will study the interaction as important physical parameters such as temperature, chemical composition and/or magnetic field are varied in a controlled manner.
An integral part of our effort is the further development of resonant total x-ray scattering as a tool to study the local atomic structure of materials exhibiting any type of structural distortions with both high real-space resolution and chemical specificity. In particular, taking advantage of the improved capabilities of 4th generation synchrotron radiation sources, such as the Advanced Photon Source at the Argonne National laboratory, we will implement single-photon, two-dimensional detectors to facilitate the acquisition of experimental data, enabling in-situ studies. We will also develop improved experimental data processing and modeling procedures, including user-friendly software.
Results from the research will elucidate the basic physics behind fascinating phenomena in quantum materials, creating opportunities to leverage their enormous technological potential. Also, they will benefit a large community of scientists using advanced x-ray scattering techniques to study materials exhibiting structural distortions, ranging from electrolytes, glasses and nanoparticles to multiferroics, topological insulators, charge density wave systems and superconductors.
