Quasi-symmetry protected topology in a semi-metal

Abstract

The crystal symmetry of a material dictates the type of topological band structures it may host, and therefore symmetry is the guiding principle to find topological materials. Here we introduce an alternative guiding principle, which we call 'quasi-symmetry'. This is the situation where a Hamiltonian has an exact symmetry at lower-order that is broken by higher-order perturbation terms. This enforces finite but parametrically small gaps at some low-symmetry points in momentum space. Untethered from the restraints of symmetry, quasi-symmetries eliminate the need for fine-tuning as they enforce that sources of large Berry curvature will occur at arbitrary chemical potentials. We demonstrate that a quasi-symmetry in the semi-metal CoSi stabilizes gaps below 2 meV over a large near-degenerate plane that can be measured in the quantum oscillation spectrum. The application of in-plane strain breaks the crystal symmetry and gaps the degenerate point, observable by new magnetic breakdown orbits. The quasi-symmetry, however, does not depend on spatial symmetries and hence transmission remains fully coherent. These results demonstrate a class of topological materials with increased resilience to perturbations such as strain-induced crystalline symmetry breaking, which may lead to robust topological applications as well as unexpected topology beyond the usual space group classifications.

Nat. Phys. (2022)

References in corpus (43)

• Skyrmion Lattice in a Chiral Magnet
• Electronic Structure of Pyrochlore Iridates: From Topological Dirac Metal to Mott Insulator
• Weyl and Dirac Semimetals in Three Dimensional Solids
• Dirac semimetal and topological phase transitions in A3Bi (A=Na, K, Rb)
• Three Dimensional Dirac Semimetal and Quantum Transports in Cd3As2
• Topological quantum chemistry
• Giant anomalous Hall effect in a ferromagnetic Kagome-lattice semimetal
• Beyond Dirac and Weyl fermions: Unconventional quasiparticles in conventional crystals
• Quantum nonlinear Hall effect induced by Berry curvature dipole in time-reversal invariant materials
• The (High Quality) Topological Materials In The World
• Topological response in Weyl semimetals and the chiral anomaly
• Catalogue of Topological Electronic Materials
• Towards ideal topological materials: Comprehensive database searches using symmetry indicators
• Multi-Weyl Topological Semimetals Stabilized by Point Group Symmetry
• Hourglass Fermions
• Large Fermi Arcs in Unconventional Weyl Semimetal RhSi
• Transport evidence for Fermi-arc mediated chirality transfer in the Dirac semimetal Cd${}_3$As${}_2$
• Discovery of topological chiral crystals with helicoid arc states
• New classes of chiral topological nodes with non-contractible surface Fermi arcs in CoSi
• Chiral anomaly and transport in Weyl metals
• Drumhead Surface States and Topological Nodal-Line Fermions in TlTaSe2
• Chiral Topological Semimetal with Multifold Band Crossings and Long Fermi arcs
• Giant Planar Hall Effect in Topological Metals
• Giant intrinsic spin Hall effect in the TaAs family of Weyl semimetals
• Observation of Topological Photocurrents in the Chiral Weyl Semimetal RhSi
• Tuning phase transition between quantum spin Hall and ordinary insulating phases
• Unconventional mass enhancement around the Dirac nodal loop in ZrSiS
• Dirac nodal lines and induced spin Hall effect in metallic rutile oxides
• Observation and control of maximal Chern numbers in a chiral topological semimetal
• Intrinsic spin-orbit coupling gap and the evidence of a topological state in graphene
• Observation of giant spin-split Fermi-arc with maximal Chern number in the chiral topological semimetal PtGa
• Crystal growth and quantum oscillations in the topological chiral semimetal CoSi
• Quasiparticle Interference Evidence of the Topological Fermi Arc States in Chiral Fermionic Semimetal CoSi
• Symmetry-enforced topological nodal planes at the Fermi surface of a chiral magnet
• Spatially modulated heavy-fermion superconductivity in CeIrIn5
• Current-induced second harmonic generation in inversion-symmetric Dirac and Weyl semimetals
• Direct observation of handedness-dependent quasiparticle interference in the two enantiomers of topological chiral semimetal PdGa
• Correlation between Fermi surface transformations and superconductivity in the electron-doped high-$T_c$ superconductor Nd${}_{2-x}$Ce${}_x$CuO${}_4$
• Single crystal growth and magnetoresistivity study of topological semimetal CoSi
• Observation of a singular Weyl point surrounded by charged nodal walls in PtGa
• Network of topological nodal planes, multifold degeneracies, and Weyl points in CoSi
• Quantum oscillations and electronic structure in the large-Chern number topological chiral semimetal PtGa
• Topological piezoelectric effect and parity anomaly in nodal line semimetals

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• Quasi-symmetry Constrained Spin Ferromagnetism in Altermagnets
• Group Theory on Quasisymmetry and Protected Near Degeneracy
• Gapped nodal planes drive a large topological Nernst effect in a chiral lattice antiferromagnet
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• Duality,Hidden Symmetry and Dynamic Isomerism in 2D Hinge Structures
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• Chiral Floquet Engineering on Topological Fermions in Chiral Crystals
• Fermi surface of the chiral topological semimetal CoSi
• IrF4: From Tetrahedral Compass Model to Topological Semimetal
• Spin-orbit-coupled superconductivity with spin-singlet non-unitary pairing
• Quantum Geometric Origin of the Intrinsic Nonlinear Hall Effect
• Sub-symmetry Protected Topology in Topological Insulators and Superconductors
• Geometric semimetals and their simulation in synthetic matter
• Intrinsic defect intolerance in the ultra-pure metal PtSn${}_4$
• Inverse-current quantum electro-oscillations in a charge-density wave insulator
• Atomically thin obstructed atomic insulators with robust edge modes and quantized spin Hall effect
• Topological Charge Quadrupole Protected by Spin-Orbit U(1) Quasi-Symmetry in Antiferromagnet NdBiPt
• Physical Pictures for Quasisymmetry in Crystals
• Fate of Bosonic Topological Edge Modes in the Presence of Many-Body Interactions