Novel approaches to studying frustrated charge interactions in strongly correlated materials

In strongly correlated systems with frustrated lattice geometries, competing interactions between electronic degrees of freedom (e.g., spin, lattice, charge, orbital) can lead to novel and unexpected phase behaviors. Magnetic interactions, for example, across the triangular lattice network are predicted to stabilize states such as the quantum spin liquids or native disordered quantum ground states. This frustration is, however, not limited to spin interactions and the charge degree of freedom can also be impacted via forms of orbital or bond frustration. The resulting short-range, frustrated charge correlations are readily probed via single-crystal diffuse X-ray scattering – broad reciprocal space features which lie underneath or between the familiar Bragg reflections. A careful analysis of the wavevector- and temperature-dependence of these features can resolve the real-space nature and energy scale of the underlying interactions driving charge frustration. In this talk, I will discuss our recent work investigating short-range charge correlations in the kagome metal ScV₆Sn₆ and in the LnCd₃P₃ family of triangular network antiferromagnets. Using a suite of novel approaches including machine learning (X-TEC), reciprocal-space modeling (Spinteract), and real-space modeling (3D-ΔPDF / Monte Carlo), we identify both a real-space picture of the frustrated charge correlations and an effective Hamiltonian which maps the corresponding interactions in each system to a J₁-J₂-J₃ antiferromagnetic Ising model on a triangular lattice.