Universal Mott quantum criticality in a modified periodic Anderson model

Mott quantum criticality is a central theme in correlated electron physics, with comparable critical exponents observed in materials featuring both continuous zero-temperature transitions and those with finite-temperature critical endpoints. Such criticality was first predicted theoretically for the single-band Hubbard model (SBHM). Within dynamical mean-field theory (DMFT), the SBHM undergoes a first-order transition at $T=0$, but displays quantum critical scaling above its finite-temperature critical point. However, a comprehensive analysis of a system exhibiting a continuous Mott transition at zero temperature has been lacking. To this end, the modified periodic Anderson model (MPAM) is a rare example known to host a surface of continuous Mott quantum critical points (QCPs). While previous studies of the MPAM characterized its QCP and showed the emergence of a pseudogap Anderson model at the QCP, the analysis was restricted to the Matsubara frequency axis, leaving key questions unresolved: What are the signatures of Mott quantum criticality in transport properties, and do the critical exponents align with the universal behavior seen in the SBHM and experiments? To address these questions, we employ DMFT with the numerical renormalization group as an impurity solver to investigate the real-frequency properties of the MPAM. Our central finding is the emergence of quantum critical scaling in the electrical resistivity, with exponents $\ensuremath{\nu}{z}_{\text{met}}\ensuremath{\approx}0.76$ and $\ensuremath{\nu}{z}_{\text{ins}}\ensuremath{\approx}0.66$ on the metallic and insulating sides, respectively. These values fall within the range reported for the SBHM and observed in experiments, suggesting that both transitions are governed by a common universality class. We further substantiate the presence of local quantum criticality by demonstrating robust $\ensuremath{\omega}/T$ scaling in single- and two-particle correlation functions. Finally, we identify different signatures in the optical conductivity, where the distinct evolution of two isosbestic points provides a unique fingerprint of Mott quantum criticality. These results establish the MPAM as a canonical model for investigating Mott quantum criticality and support the existence of a universal framework for this fundamental phenomenon.