Search

By considering a nonmonotonic d-wave superconducting (SC) gap effect in electron-doped cuprate superconductors, the energy and momentum dependence of the electronic Raman scattering is studied. The electronic Raman scattering of electron-doped cuprate superconductors has obvious differences with hole-doped case described by a pure d-wave SC gap, which can be attributed to the nonmonotonic d-wave SC gap in electron-doped cuprate superconductors. Three main different behaviours for the electronic Raman scattering spectra between electron-doped and hole-doped cuprate superconductors have been obtained, the intensity comparison of B 1 g and B 2 g spectra, the Raman peak positions as a function of energy for B 1 g and B 2 g spectra, and energy asymptotic behaviour of the low-energy B 1 g spectrum. For electron-doped cuprate superconductors, the intensity of B 2 g spectrum as a function of energy is larger than B 1 g one, and the Raman peak position of B 2 g spectrum appears at a higher energy than B 1 g one, then the low-energy spectrum of B 1 g as a function of energy increases linearly, not ω 3 energy dependence. All these theoretical results of electron-doped cuprate superconductors are in qualitative agreement with the corresponding Raman scattering experimental data. [ABSTRACT FROM AUTHOR]

The correlation between the charge-order wave vector QCD and second-neighbor hopping t′ in cuprate superconductors is studied based on the t- t′- J model. It is shown that the magnitude of the charge-order wave vector QCD increases with the increase of t′, and then the experimentally observed differences of the magnitudes of the charge-order wave vector QCD among the different families of cuprate superconductors at the same doping concentration can be attributed to the different values of t′. [ABSTRACT FROM AUTHOR]

By considering the pseudogap effect, the doping and energy dependences of thermal conductivity in cuprate superconductors are studied. Our results show that the thermal conductivity as a function of energy exhibits a characteristic peak from underdoping to overdoping due to the presence of the pseudogap in pseudogap phase of cuprate superconductors. The thermal conductivity is strongly doping dependent. On the one hand, with increasing doping concentration, the weight of thermal conductivity increases quickly, especially the residual thermal conductivity which is in qualitative agreement with the experimental data. On the other hand, the characteristic energy corresponding to the position of the characteristic peak decreases monotonically upon increasing doping concentration, and it scales with the doping dependence of pseudogap. In particular, we have studied the doping dependence of the ratio of quasiparticle velocities normal and tangential to the Fermi surface at the nodes . It is shown that increases with the increase of doping concentration. Moreover, we explain that both the residual thermal conductivity and increase rapidly upon the increase in doping concentration in heavily overdoped cuprate superconductors. [ABSTRACT FROM AUTHOR]

There is a long-standing issue that the optical conductivity in normal-state of cuprate superconductors deviates the conventional Drude type marked by dependence, exhibiting two main components from underdoping to overdoping, a narrow band peaked around zero energy and a broadband centered in the mid-infrared region called mid-infrared band. Within the renormalized t- J model and self-consistent mean field theory, we discuss the doping and energy dependence of optical conductivity in cuprate superconductors. Our results show that the appearance of the pseudogap in normal state is responsible for anomalous optical conductivity, giving rise to the mid-infrared band. In particular, in analogy to the doping dependence of pseudogap, optical conductivity is also strongly doping dependent. By increasing the doping concentration, the spectral weight of the optical conductivity suppressed strongly in underdoped region increases quickly, and the peak position of the mid-infrared band moves towards to the lower energy region, then incorporates into the narrow band centered in zero energy in the heavily overdoped region. [ABSTRACT FROM AUTHOR]

Within the framework of the t- J model, the nature of the peak-dip-hump structure in the electron spectrum of cuprate superconductors in the normal-state is studied by taking into account the pseudogap effect. It is shown that in analogy to the charge-order state, the peak-dip-hump structure in the electron spectrum is also generated by the momentum dependence of the pseudogap, and therefore, there is a common origin for the emergence of the charge-order state and peak-dip-hump structure. In particular, the remarkable peak-dip-hump structure in the electron spectrum appears in the entire region of the electron Fermi surface except for the hot spots. [ABSTRACT FROM AUTHOR]

The study of superconductivity arising from doping a Mott insulator has become a central issue in the area of superconductivity. Within the framework of the kinetic-energy-driven superconducting (SC) mechanism, we discuss the thermodynamic properties in the triangular-lattice cobaltate superconductors. It is shown that a sharp peak in the specific heat appears at the SC transition temperature $$T_\mathrm{c}$$ , and then the specific heat varies exponentially as a function of temperature for temperatures $$T

The recently discovered charge order is an intrinsic and universal property of cuprate superconductors, however, its microscopic origin remains debated. Here we review briefly the theoretical work about the nature of charge order in cuprate superconductors. In particular, we show that the electron self-energy obliterates the electron Fermi surface around the antinodal region, leaving behind disconnected Fermi arcs located around the nodal region. The charge-order state on the other hand is driven by the Fermi-arc instability, with a characteristic wavevector corresponding to the hot spots of the Fermi arcs rather than the antinodal nesting vector. Since the pseudogap emanates from the electron self-energy, the Fermi arc, charge order, and pseudogap in cuprate superconductors are intimately related each other. [ABSTRACT FROM AUTHOR]

A long-standing unsolved problem is how a microscopic theory of superconductivity in cuprate superconductors based on the charge-spin separation can produce a large electron Fermi surface (EFS). Within the framework of the kinetic-energy driven superconducting mechanism, a full charge-spin recombination scheme is developed to fully recombine a charge carrier and a localized spin into an electron, and then is employed to study the electron-momentum distribution in cuprate superconductors. In particular, the theory shows that the underlying EFS fulfills Luttinger's theorem, and the sum rule for the constrained electron is obeyed. [ABSTRACT FROM AUTHOR]

Abstract: The particle–hole asymmetry electronic state of cuprate superconductors and the related doping and temperature dependence of the Fermi arc length are studied based on the kinetic energy driven superconducting mechanism. By taking into account the interplay between the superconducting gap and normal-state pseudogap, the essential feature of the evolution of the Fermi arc length with doping and temperature is qualitatively reproduced. It is shown that the particle–hole asymmetry electronic state is a natural consequence due to the presence the normal-state pseudogap in the particle–hole channel. The Fermi arc length increases with increasing temperatures below the normal-state pseudogap crossover temperature T ∗, and it covers the full length of the Fermi surface for T > T ∗. In particular, in analogy to the temperature dependence of the Fermi arc length, the low-temperature Fermi arc length in the underdoped regime increases with increasing doping, and then it evolves into a continuous contour in momentum space near the end of the superconducting dome. The theory also predicts an almost linear doping dependence of the Fermi arc length. [Copyright &y& Elsevier]

A long-standing unsolved problem is how a microscopic theory of superconductivity in cuprate superconductors based on the charge-spin separation can produce a large electron Fermi surface. Within the framework of the kinetic-energy driven superconducting mechanism, a full charge-spin recombination scheme is developed to fully recombine a charge carrier and a localized spin into a electron, and then is employed to study the electronic structure of cuprate superconductors in the superconducting-state. In particular, it is shown that the underlying electron Fermi surface fulfills Luttinger’s theorem, while the superconducting coherence of the low-energy quasiparticle excitations is qualitatively described by the standard d-wave Bardeen–Cooper–Schrieffer formalism. The theory also shows that the observed peak-dip-hump structure in the electron spectrum and Fermi arc behavior in the underdoped regime are mainly caused by the strong energy and momentum dependence of the electron self-energy. [ABSTRACT FROM AUTHOR]