Related papers: From semiconductors to superconductors: a simple m…
Thermal transport in the T -> 0 limit was measured as a function of doping in high-quality single crystals of the cuprate superconductor YBa_2Cu_3O_y. The residual linear term kappa_0/T is found to decrease as one moves from the overdoped…
We present a model of a strongly correlated system with a non-Fermi liquid high temperature phase. Its ground state undergoes an insulator to superconductor quantum phase transition (QPT) as a function of a pairing interaction strength.…
Starting from a spin-fermion model for the cuprate superconductors, we obtain an effective interaction for the charge carriers by integrating out the spin degrees of freedom. Our model predicts a quantum critical point for the…
The impact of the normal-state pseudogap, present in all optimal and underdoped HTS cuprates, on critical currents and critical temperature is surveyed. With the opening of the pseudogap around a doping state of p=0.19 the condensation…
We provide a microscopic-level derivation of earlier results showing that, in the critical vicinity of the superconductor-to-insulator transition (SIT), disorder and localization become negligible and the structure of the emergent phases is…
We first explain the pseudogap of high-temperature superconductivity based on an approach of quantum optics. After introducing a damping factor for the lifetime $\tau$ of quasiparticles, the superconducting dome is naturally produced, and…
The parent compound of the copper-oxide high temperature superconductors is a Mott insulator. Superconductivity is realized by doping an appropriate amount of charge carriers. How a Mott insulator transforms into a superconductor is crucial…
In these lectures, superconductivity in impure thin films close to the absolute zero of temperature is discussed. The behavior as function of the applied magnetic field and the amount of impurities suggests the presence of a…
We report a fine tuned doping study of strongly overdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ single crystals using electronic Raman scattering. Combined with theoretical calculations, we show that the doping, at which the normal state…
The current understanding of the superconductor-insulator transition is discussed level by level in a cyclic spiral-like manner. At the first level, physical phenomena and processes are discussed which, while of no formal relevance to the…
We study the phase diagram of a one-dimensional Hubbard model where, in addition to the standard nearest neighbor hopping $t$, we also include a next-to-nearest neighbor hopping $t'$. For strong enough on-site repulsion, this model has a…
We study the effect of doping the semiconductor with the resonance negative U-centers upon its superconducting transition temperature. The attraction of electrons at the U-centers leads to the enhancement of transition temperature. On the…
Heat transport in the cuprate superconductors YBa$_2$Cu$_3$O$_{y}$ and La$_{2-x}$Sr$_x$CuO$_4$ was measured at low temperatures as a function of doping. A residual linear term kappa_{0}/T is observed throughout the superconducting region…
We propose a simple model for superconductors endowed with two critical temperatures, corresponding to two second-order phase transitions, in the framework of the Ginzburg-Landau mean-field theory. For very large Cooper pair…
The onset of the pseudogap in high-$T_c$ superconducting cuprates (HTSC) is marked by the $T^*$ line in the doping-temperature phase diagram, which ends at a point $p^*$ at zero temperature within the superconducting dome. Although various…
A theory of strongly correlated electron or hole liquids with the fermion condensate is presented and applied to the consideration of quasiparticle excitations in high temperature superconductors, in their superconducting and normal states.…
A model for spin-charge separated superconductivity in two dimensions is introduced where the phases of the spinon and holon order parameters couple gauge-invariantly to a statistical gauge-field representing chiral spin-fluctuations. The…
We construct a 2+1 dimensional model that sustains superconductivity at all temperatures. This is achieved by introducing a Chern Simons mixing term between two Abelian gauge fields A and Z. The superfluid is described by a complex scalar…
Through the measurements of magnetic field dependence of specific heat in $La_{2-x}Sr_xCuO_4$ in zero temperature limit, we determined the nodal slope $v_\Delta$ of the quasiparticle gap. It is found that $v_\Delta$ has a very similar…
In this study, a possible non-quasiparticle glue for superconductivity of both conventional and unconventional superconductors is explored in a pure electron picture. It is shown clearly that the moving electrons due to the electromagnetic…