Observation of boundary induced chiral anomaly bulk states and their transport properties

Abstract

The robust transport of edge modes is perhaps the most useful property of topological materials. The existence of edge modes is guaranteed by the bulk-edge correspondence, which states that the number of topological edge modes is determined by the bulk topological invariants. To obtain robust transport on the edge, we need to make volumetric changes to many bulk atoms to control the properties of a few edge atoms in a lower dimension. We suggest here that we can do the reverse in some cases: the properties of the edge can guarantee chiral transport phenomena in some bulk modes, achieving phenomena that are essentially the same as those observed in topological valley-Hall systems. Specifically, we show that a topologically trivial 2D hexagonal phononic crystal slab (waveguide) bounded by hardwall boundaries guarantees the existence of bulk modes with chiral anomaly inside a pseudogap. We experimentally observed robust valley-selected transport, complete valley state conversion, and valley focusing of the chiral anomaly bulk states (CABSs) in such phononic crystal waveguides.

17 pages, 5 figures

References in corpus (6)

• The Valley Hall Effect in MoS2 Transistors
• Observation of topological valley transport of sound in sonic crystals
• Topological confinement in bilayer graphene
• Valley Vortex States in Sonic Crystals
• Edge states in Graphene: from gapped flat band to gapless chiral modes
• Electronic Highways in Bilayer Graphene

Cited by in corpus (2)

• Tunable chiral anomalies and coherent transport on a honeycomb lattice
• Chiral Anomaly Induced Transverse Planar Transport Phenomena in Three Dimensional Spin-Orbit Coupled Metals