Splitting or not splitting of the Van Hove singularity in the high T c superconductors

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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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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Evidence of strong correlations at the van Hove singularity in the scanning tunneling spectra of superconducting Bi2Sr2CaCu2O8+δsingle crystals

Physical Review B ◽

10.1103/physrevb.85.214504 ◽

2012 ◽

Vol 85 (21) ◽

Cited By ~ 14

Author(s):

Jouko Nieminen ◽

Ilpo Suominen ◽

Tanmoy Das ◽

R. S. Markiewicz ◽

A. Bansil

Keyword(s):

Scanning Tunneling ◽

Strong Correlations ◽

Van Hove Singularity

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Observing quantum-path interference and Van Hove singularity in polarization-resolved high-harmonic spectroscopy

Optics Letters ◽

10.1364/ol.419789 ◽

2021 ◽

Vol 46 (9) ◽

pp. 2007

Author(s):

Tao-Yuan Du

Keyword(s):

High Harmonic ◽

Van Hove Singularity

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THE VAN HOVE SINGULARITY IN HIGH Tc SUPERCONDUCTORS

International Journal of Modern Physics B ◽

10.1142/s0217979295000434 ◽

1995 ◽

Vol 09 (09) ◽

pp. 1067-1080 ◽

Cited By ~ 5

Author(s):

M.L. HORBACH ◽

H. KAJÜTER

Keyword(s):

Energy Scale ◽

Measured Temperature ◽

Van Hove Singularity ◽

High Tc Superconductors ◽

Electronic Density ◽

High Tc ◽

Scattering Rate ◽

Weakly Coupled ◽

Coherence Lengths

Experimental indications for the role of the van Hove singularity (vHs) in the electronic density of states of high Tc superconductors are discussed. It is argued that (i) like the resistivity, the measured temperature and doping dependences of the normal state electronic specific heat of YBCO are consistent with the existence of a vHs and (ii) the doping dependence of Tc in the underdoped and optimally doped regimes may be accounted for mainly by a vHs. Further, we discuss the suppression of the quasiparticle scattering rate below Tc, and the coherence lengths in the hole-doped materials and NCCO. Assuming that the same mechanism for superconductivity operates in the electron-doped and the hole-doped cuprates, we argue that the bosonic mode that causes the superconductivity is strongly influenced by the doping in the overdoped regime. We further argue that this boson involves an energy scale larger than that of phonons and is only weakly coupled to the charge carriers.

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