scholarly journals A Theoretical Approach to Pseudogap and Superconducting Transitions in Hole-Doped Cuprates

2013 ◽  
Vol 2013 ◽  
pp. 1-26
Author(s):  
Partha Goswami
Keyword(s):  
Excitation Spectrum ◽  
Single Particle ◽  
Momentum Space ◽  
Density Wave ◽  
Mean Field ◽  
Spectral Weight ◽  
Square Lattice ◽  
Cooper Pairs ◽  
Single Particle Excitation ◽  
Competing Orders

We consider a two-dimensional fermion system on a square lattice described by a mean-field Hamiltonian involving the singlet id-density wave (DDW) order, assumed to correspond to the pseudo-gap (PG) state, favored by the electronic repulsion and the coexisting -wave superconductivity (DSC) driven by an assumed attractive interaction within the BCS framework. Whereas the single-particle excitation spectrum of the pure DDW state consists of the fermionic particles and holes over the reasonably conducting background, the coexisting states corresponds to Bogoliubov quasi-particles in the background of the delocalized Cooper pairs in the momentum space. We find that the two gaps in the single-particle excitation spectrum corresponding to PG and DSC, respectively, are distinct and do not merge into one “quadrature” gap if the nesting property of the normal state dispersion is absent. We show that the PG and DSC are representing two competing orders as the former brings about a depletion of the spectral weight available for pairing in the anti-nodal region of momentum space where the superconducting gap is supposed to be the largest. This indicates that the PG state perhaps could not be linked to a preformed pairing scenario. We also show the depletion of the spectral weight below at energies larger than the gap amplitude. This is an important hallmark of the strong coupling superconductivity.

scholarly journals ON d+id DENSITY WAVE AND SUPERCONDUCTING ORDERINGS IN HOLE-DOPED CUPRATES

2013 ◽  
Vol 27 (13) ◽  
pp. 1330008
Author(s):  
PARTHA GOSWAMI ◽  
AJAY PRATAP SINGH GAHLOT ◽  
PANKAJ SINGH
Keyword(s):  
Chemical Potential ◽  
Density Wave ◽  
Mean Field ◽  
Spectral Weight ◽  
Quasi Particle ◽  
Scattering Rate ◽  
Consistent Manner ◽  
Single Particle Excitation ◽  
The Mean ◽  
Competing Orders

The d+id-density wave (chiral DDW) order, at the anti-ferromagnetic wave vector Q = (π, π), is assumed to represent the pseudo-gap (PG) state of a hole-doped cuprate superconductor. The pairing interaction U(k, k′) required for d+id ordering comprises of (Ux2-y2(k, k′), Uxy(k, k′)), where [Formula: see text] and [Formula: see text] with U1 > U2. The d-wave superconductivity (DSC), driven by an assumed attractive interaction of the form [Formula: see text] where V1 is a model parameter, is discussed within the mean-field framework together with the d+id ordering. The single-particle excitation spectrum in the CDDW + DSC state is characterized by the Bogoluibov quasi-particle bands — a characteristic feature of SC state. The coupled gap equations are solved self-consistently together with the equation to determine the chemical potential (μ). With the pinning of the van Hove-singularities close to μ, one is able to calculate the thermodynamic and transport properties of the under-doped cuprates in a consistent manner. The electron specific heat displays non-Fermi liquid feature in the CDDW state. The CDDW and DSC are found to represent two competing orders as the former brings about a depletion of the spectral weight (and Raman response function density) available for pairing in the anti-nodal region of momentum space. It is also shown that the depletion of the spectral weight below Tc at energies larger than the gap amplitude occurs. This is an indication of the strong-coupling superconductivity in cuprates. The calculation of the ratio of the quasi-particle thermal conductivity αxx and temperature in the superconducting phase is found to be constant in the limit of near-zero quasi-particle scattering rate.

Single-particle excitation spectrum of the anyon gas

1992 ◽  
Vol 46 (14) ◽  
pp. 9063-9069 ◽  
Author(s):  
A. L. Fetter ◽  
C. B. Hanna
Keyword(s):  
Excitation Spectrum ◽  
Single Particle ◽  
Single Particle Excitation

Pseudogap Formation in CeNiSn

1998 ◽  
Vol 12 (05) ◽  
pp. 197-204
Author(s):  
Feng Xiao-Bing
Keyword(s):  
Green’S Function ◽  
Temperature Dependence ◽  
Excitation Spectrum ◽  
Green's Function ◽  
Single Particle ◽  
Anderson Model ◽  
Periodic Anderson Model ◽  
Decoupling Method ◽  
Single Particle Excitation

Using Green's function decoupling method the single particle excitation spectrum of the periodic Anderson model is studied. With increasing hybridization potential in the Kondo regime there appear pseudogaps in the excitation spectrum of the two kinds of carriers. The temperature dependence of the pseudogaps is qualitatively in accordance with tunneling experiments on CeNiSn.

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