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The paper has been withdrawn by the author because the observed effect has a different origin.
Recent tunneling studies in Bi2Sr2CaCu2O8 suggest that the pseudogap is caused by superconducting fluctuations. By reanalyzing this data, we show that instead there is a second non-superconducting component of the gap which increases…
Tunneling measurements have been carried out on slightly overdoped Bi2212 single crystals below and above the critical temperature by break-junctions and in-plane point-contacts. An anomaly was found in the tunneling I(V) characteristics.…
Tunneling measurements have been carried out on heavily underdoped and slightly overdoped Bi2212 single crystals by using a break-junction technique. We find that in-plane tunneling spectra below Tc are the combination of incoherent part…
Tunneling measurements have been carried out on heavily underdoped, slightly overdoped and partially Ni-substituted Bi2212 single crystals by using a break-junction technique. We find that in-plane tunneling spectra below Tc are the…
New tunneling data are reported in underdoped Bi2Sr2CaCu2O8-d using superconductor-insulator-superconductor break junctions. Energy gaps, Delta, of 51+2, 54+2 and 57+3 meV are observed for three crystals with Tc=77, 74, and 70 K…
We present electron-tunneling spectroscopy of oxygen over- and under-doped Bi-2212 single crystals in a temperature range between 14 K and 290 K using a break-junction technique. In over- and under-doped samples we observe a pseudogap with…
We present electron-tunneling spectroscopy of slightly overdoped Bi2212 single crystals at low temperature using a break-junction technique. Below Tc, we observe, at least, two different superconducting gaps. We show that (i) the largest…
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…
Recent tunneling observations of a pseudogap in Bi_2Sr_2CaCu_2O_{8+delta} are not necessarily evidence that the pseudogap is associated with superconducting fluctuations. The data are here analyzed as a competition between superconductivity…
We perform a detailed study of temperature, bias and doping dependance of interlayer transport in the layered high temperature superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. We observe that the shape of interlayer characteristics in…
In a recent paper (Phys. Rev. {\bf B 67}, 094502 (2003)) Mao et al. investigated the bias-dependent conductance of mechanical junctions between superconducting MgCNi$_3$ and a sharp W tip. They interpreted their results in terms of…
The point contact tunneling technique is used to examine quasiparticle and Josephson currents in overdoped Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ (Bi-2212) single crystals with bulk T$_{c}$ values near 62 K. High quality…
This report describes some transport and magnetic properties of doped Bi2212 and Bi2223 superconducting whiskers. These materials have advantages over polycrystalline sample as well as large bulk crystals in that they provide narrow…
The interpretation of tunneling data in a recent Letter by Zasadzinski et al. is incorrect.
We present results of Raman scattering experiments in differently doped Bi-2212 single crystals. Below Tc the spectra show pair-breaking features in the whole doping range. The low frequency power laws confirm the existence of a…
In a recent article, Alldredge et al. reported tunnelling data obtained at T = 4.2 K by STM in Bi-2212 having different doping levels, p, and a new way to fit the measured differential conductances, g(V), which are linearly proportional to…
Interlayer tunneling spectroscopy measurements were performed on mesa arrays of Bi-2212 single crystals, intercalated with HgBr$_2$. Tunneling conductances were obtained over a wide temperature range to examine the spectral features,…
We use Ar-ion milling to thin Bi2212 single crystals down to a few nanometers or one-to-two (CuO2)2 layers. With decreasing the thickness, superconducting transition temperature gradually decreases to zero and the in-plane resistivity…
Although their crystal structures are complex, all high temperature superconductors contain some crystal planes consisting of only Cu and O atoms in a square lattice. Superconductivity is believed to originate from strongly interacting…