83 research outputs found
Origin of dips in tunneling dI/dV characteristics of cuprates
Extensive efforts have been made to understand the electronic properties of
high-Tc superconductors. One feature which has been discussed in the literature
during the past few years is the dips in tunneling conductances obtained in
cuprates. In this contribution, we focus our attention on the origin of these
dips. On the basis of experimental data obtained in Bi2Sr2CaCu2O8 and
YBa2Cu3O7, we show that the dips appear naturally in tunneling spectra due to a
superposition of the peaks and humps and, therefore, have no physical meaning.Comment: 2 pages including 3 figures. To appear in Physica C (proceedings of
the M2S-VIII Dresden Conference
A possible scenario for the mechanism of high-Tc superconductivity based on experimental data
The issue of the mechanism of high-Tc superconductivity remains open. In this
contribution, we propose a new scenario for the mechanism of superconductivity
in cuprates based on analysis of experimental data, mainly tunneling, neutron
scattering and muon-spin-relaxation data, made earlier (see e.g. Mod. Phys.
Lett. B 19 (2005) 743). A specific feature of this scenario is the mechanism of
the establishment of long-range phase coherence among Cooper pairs, based on
recent experimental data obtained in nonsuperconducting materials.Comment: 2 pages with 2 figures (Dresden conference
The Effect of Ni and Zn Doping in Bi2212 from Tunneling Measurements. The MCS model of the High-Tc Superconductivity in hole-doped cuprates
We use Ni and Zn impurities doped into Bi2212 to test the MS (Magnetic
polaron - Spinon) model proposed earlier. We present electron-tunneling
spectroscopy of pure, Ni- and Zn-doped Bi2212 single crystals below Tc using a
break-junction technique. We show that the magnetic (Ni) and nonmagnetic (Zn)
impurities doped into CuO2 planes affect both Tc and the density of states in
Bi2212 but do it differently. In order to explain the data, we had to modify
the MS model. Thus, we present a Magnetic Coupling of Stripes (MCS) model. In
the MCS model, there is only one superconductivity - a spinon superconductivity
along charged stripes. The coherent state of the spinon superconductivity is
established by magnons which are excited by motions of charged stripes. So, in
the MCS model, the superconductivity has two mechanisms: along charged stripes
and perpendicular to stripes.Comment: 24 pages (11 figures
The Mechanism of High-Tc Superconductivity: "Nonlinear" Superconductivity
The main purpose of the paper is to present an overview of the current
situation in the development of understanding of the mechanism of high-Tc
superconductivity which arises due to moderately strong, nonlinear
electron-phonon interactions and due to magnetic (spin) fluctuations.Comment: 9 page
The pseudogap in Bi2212 single crystals from tunneling measurements: a possible evidence for the Cooper pairs above Tc
We present electron-tunneling spectroscopy of slightly overdoped Bi2212
single crystals with Tc = 87 - 90 K in a temperature range between 14 K and 290
K using a break-junction technique. The pseudogap which has been detected above
Tc appears at T* = 280 K. The analysis of the spectra shows that there is a
contribution to the pseudogap above Tc, which disappears approximately at 110 -
115 K. We associate this contribution with the presence of incoherent Cooper
pairs.Comment: 12 pages including 4 figures, to be published in Europhysics Letter
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