Determining the dimensionality and origin of quantum criticality in quasi-2D heavy fermion Ce₂PdAl₇Ge₄ and Ce₂CoAl₇Ge₄

Quantum critical points (QCPs) are of immense importance within strongly correlated electron physics. While experimental realization is well-established, uniting experiment with theory to describe such emergence has proven to be a long-standing challenge. This is partially due to computational limitations precluding solutions for many-body techniques in 3D heavy fermion systems, necessitating experimental focus towards lower dimensional systems. The quasi-2D HF compounds Ce₂PdAl₇Ge₄ and Ce₂CoAl₇Ge₄. that crystallize with a layered structure and exhibit distinct ground states—non-Fermi liquid behavior in Pd and antiferromagnetic order in Co, are candidate systems in which to investigate heavy fermion physics in reduced dimensionality. Macroscopic physical property studies reveal these systems are proximal to QCPs and magnetic/non-magnetic boundaries with density functional theory calculations predicting quasi-2D Fermi surfaces. To elucidate the microscopic origins for the observed localized vs. itinerant behavior, we propose a high-resolution angle-resolved photoemission spectroscopy study at the LOREA beamline. We will map the dimensionality, Fermi surface topology, and decipher surface vs. bulk states. Complementary X-ray absorption and resonant photoemission spectroscopy will determine f-electron occupancy, informing dynamical mean-field theory models. This work will establish a benchmark dataset for low-dimensional HF physics, providing insights into quantum criticality and emergent many-body effects in the 2D Kondo lattices.