Higher-order Dirac sonic crystals

Abstract

Discovering new topological phases of matter is a major theme in fundamental physics and materials science. Dirac semimetal provides an exceptional platform for exploring topological phase transitions under symmetry breaking. Recent theoretical studies have revealed that a three-dimensional Dirac semimetal can harbor fascinating hinge states, a higher-order topological manifestation not known before. However, its realization in experiment is yet to be achieved. In this Letter, we propose a minimum model to construct a spinless higher-order Dirac semimetal protected by C_6v symmetry. By breaking different symmetries, this parent phase transitions into a variety of novel topological phases including higher-order topological insulator, higher-order Weyl semimetal, and higher-order nodal-ring semimetal. Furthermore, for the first time, we experimentally realize this unprecedented higher-order topological phase in a sonic crystal and present an unambiguous observation of the desired hinge states via momentun-space spectroscopy and real-space visualization. Our findings may offer new opportunities to manipulate classical waves such as sound and light.

arXiv commentAccepted by PRL

References in corpus (48)

• Topological Insulators
• Topological insulators and superconductors
• Electronic Structure of Pyrochlore Iridates: From Topological Dirac Metal to Mott Insulator
• Weyl and Dirac Semimetals in Three Dimensional Solids
• Topological Photonics
• Topological Photonics
• Discovery of a Weyl Fermion Semimetal and Topological Fermi Arcs
• Type-II Weyl Semimetals
• Quantized Electric Multipole Insulators
• Dirac semimetal and topological phase transitions in A3Bi (A=Na, K, Rb)
• Experimental discovery of Weyl semimetal TaAs
• Higher-Order Topological Insulators
• Electric Multipole Moments, Topological Multipole Moment Pumping, and Chiral Hinge States in Crystalline Insulators
• $(d-2)$-dimensional edge states of rotation symmetry protected topological states
• Topolectrical circuit realization of topological corner modes
• Reflection symmetric second-order topological insulators and superconductors
• Observation of a phononic quadrupole topological insulator
• Higher-order topological insulators and semimetals on the breathing Kagome and pyrochlore lattices
• Acoustic higher-order topological insulator on a Kagome lattice
• Demonstration of a quantized microwave quadrupole insulator with topologically protected corner states
• Quantization of fractional corner charge in $C_n$-symmetric higher-order topological crystalline insulators
• Visualization of higher-order topological insulating phases in two-dimensional dielectric photonic crystals
• Direct observation of corner states in second-order topological photonic crystal slabs
• Topological protection of photonic mid-gap cavity modes
• Photonic quadrupole topological phases
• Observation of second-order topological insulators in sonic crystals
• Corner states of light in photonic waveguides
• Elastic higher-order topological insulator with topologically protected corner states
• Higher-Order Topology, Monopole Nodal Lines, and the Origin of Large Fermi Arcs in Transition Metal Dichalcogenides XTe${}_2$ (X=Mo,W)
• Structured Weyl Points in Spin-Orbit Coupled Fermionic Superfluids
• Acoustic realization of quadrupole topological insulators
• Surface State Magnetization and Chiral Edge States on Topological Insulators
• A fractional corner anomaly reveals higher-order topology
• Strong and Fragile Topological Dirac Semimetals with Higher-Order Fermi Arcs
• Higher Order Topological Phases: A General Principle of Construction
• Observation of Quadrupole Transitions and Edge Mode Topology in an LC network
• Higher-Order Weyl Semimetals
• Observation of an acoustic octupole topological insulator
• Topological Quadrupolar Semimetals
• Demonstration of a quantized acoustic octupole topological insulator
• Higher-order topological semimetal in acoustic crystals
• Higher-order Weyl Semimetals
• Dimensional hierarchy of higher-order topology in three-dimensional sonic crystals
• Observation of a phononic higher-order Weyl semimetal
• Antiunitary symmetry protected higher order topological phases
• Higher-Order Topological Dirac Superconductors
• Higher-order topological insulators and semimetals in generalized Aubry-André-Harper models
• Discovering topological surface states of Dirac points

Cited by in corpus (21)

• Topological acoustics
• Acoustic Higher-Order Weyl Semimetal with Bound Hinge States in the Continuum
• Square-root higher-order Weyl semimetals
• Higher-order Dirac Semimetal in a Photonic Crystal
• Topological Phases in Magnonics
• Higher-order topological phases in crystalline and non-crystalline systems: a review
• Realization of Surface-Obstructed Topological Insulators
• Stiefel-Whitney topological charges in a three-dimensional acoustic nodal-line crystal
• Observation of Large-Number Corner Modes in $\mathbb{Z}$-class Higher-Order Topolectrical Circuits
• Engineering second-order topological insulators via coupling two first-order topological insulators
• Universal higher-order bulk-boundary correspondence of triple nodal points
• Topological hinge modes in Dirac semimetals
• Hinge mode dynamics of periodically driven higher-order Weyl semimetals
• Observation of squeezed Chern insulator in an acoustic fractal lattice
• Dynamical Detection of Topological Spectral Density
• Stable Higher-Order Topological Dirac Semimetals with ${\mathbb{Z}}_2$ Monopole Charge in Alternating-twisted Multilayer Graphenes and beyond
• Multi higher-order Dirac and nodal line semimetals
• Microwave hinge states in a simple-cubic-lattice photonic crystal insulator
• Topological semimetal with coexisting nodal points and nodal lines
• Floquet composite Dirac semimetals
• Non-Hermitian Higher-Order Dirac Semimetals