Emergence of Non-Fermi Liquid Behavior with Quantum Criticality in Transition Metal Dichalcogenides

Unraveling the microscopic origins of non-Fermi liquid behavior near a quantum critical point (QCP) remains a central puzzle in condensed matter physics. A key challenge lies in disentangling the often-coexisting roles of Coulomb interactions and disorder. Here, we use transition metal dichalcogenides (TMDs)─PdSe2, WSe2, and MoS2─as prototypes to understand how Coulomb interactions and disorder govern the electrical resistivity of metals near the QCP. We show that resistivity exhibits Fermi liquid behavior at low temperatures and T-linear resistivity at intermediate temperatures in the deep metallic phase of these systems. As the metal-insulator boundary approaches, the low-temperature Fermi liquid phase turns into the T-linear resistivity in PdSe2 and transitions to an electron glass in WSe2 and MoS2 by increasing the strength of Coulomb interactions and degree of disorder. Further, resistivity develops distinct nonmonotonic T-dependencies in these systems while approaching the metal-insulator boundary, suggesting different microscopic origins of resistivity. This dichotomy is corroborated by quantum critical scaling, which reveals divergent universality classes. This study establishes TMDs as a promising platform for understanding the interplay between Coulomb interactions and disorder in the quantum critical regime.