arXiv subjects

Anzhuoer Li

Publications and source records attributed to Anzhuoer Li.

3 recordsLinked to original sources

arXiv2026

Microwave Imaging of Edge Conductivity in Graphene at Charge Neutrality and Quantum Hall States

We report local conductivity imaging of edge states in monolayer graphene by millikelvin microwave impedance microscopy (MIM). At the charge-neutrality point, as the magnetic field increases, the local conductivity at the edge drops to zero more slowly than in the bulk. This behavior is consistent with the calculated spatial profile of the charge gap in the canted antiferromagnetic phase. For comparison, we also perform microwave imaging of integer quantum Hall states away from neutrality, which host dissipationless chiral edge channels. The evolution of the edge signal as a function of the bulk gap is fundamentally different between the Landau level filling factor $ν= 0$ and $|ν| \ge 1$ integer quantum Hall states, which can be qualitatively explained by numerical simulations and theoretical analysis. Our results provide a comprehensive microscopic picture of the edge and bulk states as the Fermi level moves across the unique Landau-level spectrum of graphene.

cond-mat.str-el↗

arXiv2025

Valley Order in Moiré Topological Insulators

Moiré materials with opposite non-zero miniband Chern numbers in time-reversal-partner valleys are two-dimensional topological insulators at band filling $ν=2$. We explore the possibility that in this class of moir'e materials intervalley coherence can sometimes be present in interaction induced insulators at band filling $ν=1$ , using Landau levels with opposite signs of the magnetic field as a convenient generic model. In the absence of intravalley interactions the mean-field ground state at filling factor $ν=1$ is a gapless intervalley coherent state that maps under a particle-hole transformation of one valley to a strong-field superconducting vortex-lattice state that has been studied previously. When the ratio $λ$ of intravalley to intervalley interactions is increased, gapped states appear, one with broken time-reversal symmetry and a quantized Hall effect but no valley polarization and one with broken parity symmetry and zero Hall conductivity. We discuss the possibility that the latter state could be related to the fractional quantum spin Hall effect recently observed at an odd filling factor in a moir'e topological insulator and comment on related systems in which correlations between electrons in bands with opposite Chern numbers might play a key role.

cond-mat.mes-hall↗

arXiv2025

Geodynamics and artificial gravity in space-time crystals under slow perturbation and deformation

We present a theory of geodynamics in a space-time crystal based on an event wave packet constructed from the Floquet-Bloch waves, which not only involve a scalar dispersion function but also a Berry curvature tensor in the phase space manifold of space-time and the reciprocal quasi energy-momentum. In the presence of structural deformation, this theory is naturally extended into a covariant form with the introduction of a lattice connection constructed out of the gradients of the local lattice vectors. The geodesic equation for a particle not only involves the lattice connection but also higher-order corrections from space-time inhomogeneity of Berry curvatures and quasi energy-momentum dispersion gradients. These emergent connections and metric terms in the geodesic equations indicate the potential to experimentally realize artificial gravitational effects, thereby establishing a direct conceptual link between general relativity and quantum theory.

cond-mat.mtrl-sci↗