Strange metal phase of disordered magic-angle twisted bilayer graphene at low temperatures: from flatbands to weakly coupled Sachdev-Ye-Kitaev bundles

Abstract

We use stochastic expansion and exact diagonalization to study the magic-angle twisted bilayer graphene (TBG) on a disordered substrate. We show that the substrate-induced strong Coulomb disorder in TBG with the chemical potential at the level of the flatbands drives the system to a network of weakly coupled Sachdev-Ye-Kitaev (SYK) bundles, stabilizing an emergent quantum chaotic strange metal (SM) phase of TBG that exhibits the absence of quasiparticles. The Gaussian orthogonal ensemble dominates TBG's long-time chaotic dynamics at strong disorder, whereas fast quantum scrambling appears in the short-time dynamics. In weak disorder, gapped phases of TBG exhibit exponentially decaying specific heat capacity and exponential decay in out-of-time-ordered correlators (OTOC). This is the system behavior in correlated insulator and superconducting phases, in agreement with the corresponding Larkin-Ovchinnikov result for correlators. The result suggests a low-temperature transition from the superconducting and correlated insulating phases into the strange metal upon increasing the disorder strength. We propose a finite-temperature phase diagram for Coulomb-disordered TBG and discuss the experimental consequences of the emergent SM phase.

10 pages, 5 figures

References in corpus (25)

• The Kernel Polynomial Method
• Evidence for unconventional superconductivity in twisted bilayer graphene
• Spectral and thermodynamic properties of the Sachdev-Ye-Kitaev model
• Quantum critical behavior in magic-angle twisted bilayer graphene
• Planckian Dissipation in Metals
• Composite fermion state of spin-orbit coupled bosons
• Coulomb disorder in three-dimensional Dirac systems
• Spontaneous formation of a non-uniform chiral spin liquid in moat-band lattices
• Reconciling scaling of the optical conductivity of cuprate superconductors with Planckian resistivity and specific heat
• Excitonic topological order in imbalanced electron-hole bilayers
• Flat band carrier confinement in magic-angle twisted bilayer graphene
• Violation of bound on chaos for charged probe in Kerr-Newman-AdS black hole
• Transport across twist angle domains in moiré graphene
• Dynamical properties of collective excitations in twisted bilayer Graphene
• Quantum critical Eliashberg theory, the SYK superconductor and their holographic duals
• Superconductivity of incoherent electrons in Yukawa-SYK model
• A simple model of Coulomb disorder and screening in graphene
• Nature of Protected Zero Energy States in Penrose Quasicrystals
• Fermionic propagators for 2D systems with singular interactions
• High transmission in twisted bilayer graphene with angle disorder
• Maximal quantum chaos of the critical Fermi surface
• Chiral spin liquid state of strongly interacting bosons with a moat dispersion: a Monte Carlo simulation
• Universal equilibration dynamics of the Sachdev-Ye-Kitaev model
• Replica Symmetry Breaking for the Integrable Two-Site Sachdev-Ye-Kitaev Model
• Zero-bias tunneling anomaly in a clean 2D electron gas caused by smooth density variations

Cited by in corpus (5)

• Stabilizer Entropy and entanglement complexity in the Sachdev-Ye-Kitaev model
• Torsional Force Microscopy of Van der Waals Moirés and Atomic Lattices
• Isolated flat bands in 2D lattices based on a novel path-exchange symmetry
• Trapping Hard-Core Bosons in Flatband Lattices
• Flat Bands in Three-dimensional Lattice Models with Non-trivial Hopf Index