Gap anisotropy and van Hove singularities in high-Tc superconductors

1996 ◽  
Author(s):  
Julien Bok ◽  
Jacqueline Bouvier
Keyword(s):  
Van Hove Singularities ◽  
Gap Anisotropy

SUPERCONDUCTIVITY IN CUPRATES, THE VAN HOVE SCENARIO

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3425-3430 ◽  
Author(s):  
J. Bok ◽  
J. Bouvier
Keyword(s):  
Experimental Data ◽  
Magnetic Susceptibility ◽  
Physical Properties ◽  
Fermi Level ◽  
Specific Heat ◽  
Electron Interaction ◽  
Van Hove Singularities ◽  
Underdoped Regime ◽  
Gap Anisotropy ◽  
Van Hove Scenario

The existence of van Hove singularities close to the Fermi level in all high T c cuprates has been experimentally established. We develop a theory using these singularities which enables us to compute the main physical properties: T c gap and gap anisotropy, specific heat and magnetic susceptibility. All these results agree well with the experimental data in the optimal and overdoped regime. In the underdoped regime, we use the theory of electron-electron interaction in disordered conductors to explain the pseudo-gap behaviour.

scholarly journals Spin–valley Hall phenomena driven by Van Hove singularities in blistered graphene

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
M. Umar Farooq ◽  
Arqum Hashmi ◽  
Tomoya Ono ◽  
Li Huang
Keyword(s):  
First Principles ◽  
Opposite Sign ◽  
Spin Splitting ◽  
First Principles Calculations ◽  
Van Hove Singularities ◽  
Spin Degree ◽  
Hall Effects ◽  
Back Scattering ◽  
Structural Deformations ◽  
Spin Momentum

AbstractUsing first-principles calculations, we investigate the possibility of realizing valley Hall effects (VHE) in blistered graphene sheets. We show that the Van Hove singularities (VHS) induced by structural deformations can give rise to interesting spin–valley Hall phenomena. The broken degeneracy of spin degree of freedom results in spin-filtered VH states and the valley conductivity have a Hall plateau of ±e2/2h, while the blistered structures with time-reversal symmetry show the VHE with the opposite sign of $$\sigma _{xy}^{K/K^{\prime}}$$ σ x y K / K ′ (e2/2h) in the two valleys. Remarkably, these results show that the distinguishable chiral valley pseudospin state can occur even in the presence of VHS induced spin splitting. The robust chiral spin–momentum textures in both massless and massive Dirac cones of the blistered systems indicate significant suppression of carrier back-scattering. Our study provides a different approach to realize spin-filtered and spin-valley contrasting Hall effects in graphene-based devices without any external field.

Dependence of the Second-order G'-band Profile on the Electronic Structure of Single-wal Nanotubes

2001 ◽  
Vol 706 ◽  
Author(s):  
A. G. Souza Filho ◽  
A. Joribo ◽  
G. Dresselhaus ◽  
M. S. Dresselhaus ◽  
A. K. Swan ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electronic Structure ◽  
Raman Spectra ◽  
Density Of States ◽  
Resonance Raman ◽  
Second Order ◽  
Electronic Density ◽  
Van Hove Singularities ◽  
Band Profile ◽  
Resonance Raman Spectra

AbstractWe analyze the dependence of the second-order G'-band profile in terms of their (n,m) indices by measuring the resonance Raman spectra of several semiconducting and metalic isolated single wal carbon nanotubes. We show that this profile is very sensitive to the electronic structure, thus making it possible to get structural (n,m) information and to probe the splitting of the van Hove singularities in the electronic density of states due to the trigona warping effect.

Superconducting gap anisotropy caused by a spin-density wave

1988 ◽  
Vol 61 (16) ◽  
pp. 1885-1888 ◽  
Author(s):  
A. W. Overhauser ◽  
L. L. Daemen
Keyword(s):  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Superconducting Gap ◽  
Gap Anisotropy

Millimeter-Microwave Studies of Energy-Gap Anisotropy in Superconductors

1964 ◽  
Vol 136 (6A) ◽  
pp. A1471-A1480 ◽  
Author(s):  
Manfred A. Biondi ◽  
M. P. Garfunkel ◽  
Wm. A. Thompson
Keyword(s):  
Energy Gap ◽  
Gap Anisotropy
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