The Orbitally Selective Mott Phase in Electron Doped Twisted TMDs: A Possible Realization of the Kondo Lattice Model

Abstract

Moiré super-potentials in two-dimensional materials allow unprecedented control of the ratio between kinetic and interaction energy. By this, they pave the way to study a wide variety of strongly correlated physics under a new light. In particular, the transition metal dichalcogenides (TMDs) are promising candidate "quantum simulators" of the Hubbard model on a triangular lattice. Indeed, Mott and generalized Wigner crystals have been observed in such devices. Here we theoretically propose to extend this model into the multi-orbital regime by focusing on electron doped systems at filling higher than 2. As apposed to hole bands, the electronic bands in TMD materials include two, nearly degenerate species, which can be viewed as two orbitals with different effective mass and binding energy. Using realistic band-structure parameters and a slave-rotor mean-field theory, we find that an orbitally selective (OS) Mott phase can be stabilized over a wide range surrounding filling 4, where one band is locked in a commensurate Mott state, while the other remains itinerant with variable density. This scenario thus, realizes the basic ingredients in the Kondo lattice model: A periodic lattice of localized magnetic moments interacting with metallic states. We also discuss possible experimental signatures of the OS Mott state.

Gate-tunable heavy fermion quantum criticality in a moiré Kondo lattice

“…We discuss experimental probes of Kondo lattice physics in moiré materials that discriminate among various competing antiferromagnetic (AFM) and quantum spin-liquid (QSL) weak Kondo-coupling scenarios, highlighting electrical and thermal Hall transport, and electrostatic measurements of entropy. Compared to previous proposals for achieving heavy fermion physics in moiré systems, our setup directly implements a Kondo lattice model using already-demonstrated moiré ingredients; it avoids both topological obstacles [9][10][11][12] to local-moment physics of proposed twisted graphene multilayer realizations [13], as well as the need for unusual spontaneous orbital selectivity required to form local moments in electron-doped TMD heterobilayers [14].…”