Doping a Mott insulator in an Ising-Kondo lattice: Strange metal and Mott criticality

Metallic quantum states coined strange metal (SM), with robust linear-T resistivity, have been widely observed in many quantum materials under strong electron correlations, ranging from high-Tc cuprate superconductors and organic superconductors to twisted multilayer graphene and MoTe2/WSe2 superlattices. Despite decades of intensive studies, the mystery of SM still defies any sensible theoretical explanation and has been a key puzzle in modern condensed matter physics. Here, we solve a doped Mott insulator model called an Ising-Kondo lattice, which includes static spin fluctuation. With Monte Carlo simulation, the Ising-Kondo lattice unambiguously exhibits SM phenomena accompanied with quantum critical scaling in observables, e.g., resistivity, susceptibility, and specific heat. A closer look at SM reveals the breakdown of Landau's Fermi liquid theory without any symmetry breaking, i.e., the violation of Luttinger theorem. Our paper reveals that the long-overlooked static fluctuations in literature may play an essential role in non-Fermi liquid behaviors in correlated electron systems.