Twofold van Hove singularity and origin of charge order in topological kagome superconductor CsV3Sb5

AbstractTime reversal symmetric (TRS) invariant topological insulators (TIs) fullfil a paradigmatic role in the field of topological materials, standing at the origin of its development. Apart from TRS protected strong TIs, it was realized early on that more confounding weak topological insulators (WTI) exist. WTIs depend on translational symmetry and exhibit topological surface states only in certain directions making it significantly more difficult to match the experimental success of strong TIs. We here report on the discovery of a WTI state in RhBi2 that belongs to the optimal space group P$$\bar{1}$$ 1 ¯ , which is the only space group where symmetry indicated eigenvalues enumerate all possible invariants due to absence of additional constraining crystalline symmetries. Our ARPES, DFT calculations, and effective model reveal topological surface states with saddle points that are located in the vicinity of a Dirac point resulting in a van Hove singularity (VHS) along the (100) direction close to the Fermi energy (EF). Due to the combination of exotic features, this material offers great potential as a material platform for novel quantum effects.

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Control of charge order melting through local memristive migration of oxygen vacancies

Physical Review Materials ◽

10.1103/physrevmaterials.2.054412 ◽

2018 ◽

Vol 2 (5) ◽

Cited By ~ 1

Author(s):

Zhi-Hong Wang ◽

Q. H. Zhang ◽

G. Gregori ◽

G. Cristiani ◽

Y. Yang ◽

...

Keyword(s):

Oxygen Vacancies ◽

Charge Order

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Magnetotransport of dirty-limit van Hove singularity quasiparticles

Communications Physics ◽

10.1038/s42005-020-00504-0 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Yang Xu ◽

František Herman ◽

Veronica Granata ◽

Daniel Destraz ◽

Lakshmi Das ◽

...

Keyword(s):

Electron Scattering ◽

Fermi Liquid ◽

Inelastic Electron ◽

Density Of State ◽

Strontium Ruthenate ◽

Van Hove Singularity ◽

Strong Variation ◽

Electronic Density ◽

Dirty Limit ◽

Liquid Behavior

AbstractTuning of electronic density-of-states singularities is a common route to unconventional metal physics. Conceptually, van Hove singularities are realized only in clean two-dimensional systems. Little attention has therefore been given to the disordered (dirty) limit. Here, we provide a magnetotransport study of the dirty metamagnetic system calcium-doped strontium ruthenate. Fermi liquid properties persist across the metamagnetic transition, but with an unusually strong variation of the Kadowaki-Woods ratio. This is revealed by a strong decoupling of inelastic electron scattering and electronic mass inferred from density-of-state probes. We discuss this Fermi liquid behavior in terms of a magnetic field tunable van Hove singularity in the presence of disorder. More generally, we show how dimensionality and disorder control the fate of transport properties across metamagnetic transitions.

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Van Hove singularity in the magnon spectrum of the antiferromagnetic quantum honeycomb lattice

Nature Communications ◽

10.1038/s41467-020-20335-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

G. Sala ◽

M. B. Stone ◽

Binod K. Rai ◽

A. F. May ◽

Pontus Laurell ◽

...

Keyword(s):

Disordered Systems ◽

Inelastic Neutron Scattering ◽

Magnetic Moments ◽

Wave Theory ◽

Inelastic Neutron ◽

Quantum Spin ◽

Honeycomb Lattice ◽

Quantum Magnetism ◽

Van Hove Singularity ◽

Sharp Feature

AbstractIn quantum magnets, magnetic moments fluctuate heavily and are strongly entangled with each other, a fundamental distinction from classical magnetism. Here, with inelastic neutron scattering measurements, we probe the spin correlations of the honeycomb lattice quantum magnet YbCl3. A linear spin wave theory with a single Heisenberg interaction on the honeycomb lattice, including both transverse and longitudinal channels of the neutron response, reproduces all of the key features in the spectrum. In particular, we identify a Van Hove singularity, a clearly observable sharp feature within a continuum response. The demonstration of such a Van Hove singularity in a two-magnon continuum is important as a confirmation of broadly held notions of continua in quantum magnetism and additionally because analogous features in two-spinon continua could be used to distinguish quantum spin liquids from merely disordered systems. These results establish YbCl3 as a benchmark material for quantum magnetism on the honeycomb lattice.

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