Superconductivity and strong interactions in a tunable moiré quasicrystal

Nature · 2023 · 143 citations

• Condensed matter physics
• Physics
• Materials science

Quantum metric nonlinear Hall effect in a topological antiferromagnetic heterostructure

Science · 2023 · 277 citations

• Physics
• Condensed matter physics
• Quantum mechanics

with black phosphorus. The quantum metric nonlinear Hall effect switches direction upon reversing the antiferromagnetic (AFM) spins and exhibits distinct scaling that is independent of the scattering time. Our results open the door to discovering quantum metric responses predicted theoretically and pave the way for applications that bridge nonlinear electronics with AFM spintronics.

Layer Hall effect in a 2D topological axion antiferromagnet

Nature · 2021 · 269 citations

• Condensed matter physics
• Physics
• Quantum mechanics

Continuous Mott transition in semiconductor moire superlattices

Nature · 2021 · 276 citations

• Condensed matter physics
• Physics
• Quantum mechanics

DMFT Reveals the Non-Hermitian Topology and Fermi Arcs in Heavy-Fermion Systems

Physical Review Letters · 2020 · 96 citations

• Physics
• Quantum mechanics

When a strongly correlated system supports well-defined quasiparticles, it allows for an elegant one-body effective description within the non-Hermitian topological theory. While the microscopic many-body Hamiltonian of a closed system remains Hermitian, the one-body quasiparticle Hamiltonian is non-Hermitian due to the finite quasiparticle lifetime. We use such a non-Hermitian description in the heavy-fermion two-dimensional systems with the momentum-dependent hybridization to reveal a fascinating phenomenon which can be directly probed by the spectroscopic measurements, the bulk "Fermi arcs." Starting from a simple two-band model, we first combine the phenomenological approach with the perturbation theory to show the existence of the Fermi arcs and reveal their connection to the topological exceptional points, special points in the Brillouin zone where the Hamiltonian is nondiagonalizable. The appearance of such points necessarily requires that the electrons belonging to different orbitals have different lifetimes. This requirement is naturally satisfied in the heavy-fermion systems, where the itinerant c electrons experience much weaker interaction than the localized f electrons. We then utilize the dynamical mean field theory to numerically calculate the spectral function and confirm our findings. We show that the concept of the exceptional points in the non-Hermitian quasiparticle Hamiltonians is a powerful tool for predicting new phenomena in strongly correlated electron systems.