Disorder-driven intermediate state in the lattice melting transition of Bi2Sr2CaCu2O8+delta single crystals

Oral, Ahmet
Ooi, S
Taoka, H
Tamegai, T
Henini, M
Scanning Hall probe microscopy has been used to study high quality single crystals of the Bi2Sr2CaCu2O8+delta high-temperature superconductor over a wide range of temperatures at low fields. We observe pronounced stripes of high flux density which persist well above the melting line almost up to the critical temperature of the crystal. We show that these regions impose a disorder-driven intermediate state on the vortex lattice melting transition with a structure composed of alternating solid and liquid strips. We propose that the striping may reflect regions of slightly different oxygen doping level formed due to enhanced diffusion at the edges of atomic terraces during crystal growth. We are unable to resolve discrete vortices in the stripes above the vortex lattice melting line. We speculate either that the vortex liquid efficiently screens any pinned flux present or that spatial variations in the Gibbs free energy may be imposing a density modulation on the vortex liquid at these temperatures.


Vortex imaging with varying temperature revealed by SHPM on Bi(2)Sr(2)CaCu(2)O8+y
Mihalache, V.; Dede, M.; Oral, Ahmet; Sandu, V. (2008-04-01)
Scanning Hall probe microscopy with an effective spatial resolution of similar to 1 mu m has been used to investigate the vortex structures in superconducting Bi2Sr2CaCu2O8+delta single crystals in the temperature range 77.3-81.3 K and zero applied field (in the presence of the earth field). The vortex images were obtained in real time mode as the temperature increased slowly for 3.36 h. At 77.3 K, the vortices were arranged in a chain structure. With the increase of the temperature, two jumps in the vortex...
Vortex phases in magnetic fields near ab-plane in Bi2Sr2CaCu2O8+delta single crystal
Mirkovic, Jovan; Saito, Takashi; Kashiwagi, Takanari; Kakeya, Itsuhiro; Kubo, Yuimaru; Yamamoto, Takashi; Oral, Ahmet; Kadowaki, Kazuo (2010-12-01)
Vortex matter of the layered superconductors in very high magnetic fields near the ab-plane was studied by using the c-axis resistivity measurements on the mesoscopic Bi2Sr2CaCu2O8+delta single crystals. While the angular dependence of resistance exhibits the sharp lock-in features in low magnetic field region, it was found that the vortex lock-in transition becomes considerably broad in high magnetic fields, showing anomalous shoulders at 0.3 degrees away from the ab-plane. The appearance of the resistance...
Hopping conduction in Ga4Se3S layered single crystals
Qasrawi, A.F.; Hasanlı, Nızamı (Elsevier BV, 2008-11)
The conduction mechanism in Ga4Se3S single crystals has been investigated by means of dark and illuminated conductivity measurements for the first time. The temperature-dependent electrical conductivity analysis in the region of 100-350 K, revealed the dominance of the thermionic emission and the thermally assisted variable range hopping (VRH) of charged carriers above and below 170 K, respectively. The density of states near the Fermi level and the average hopping distance for this crystal in the dark were...
Vortex imaging in superconducting films by Scanning Hall Probe Microscopy
Oral, Ahmet; HUMPHREYS, R G; HENİNİ, M (Springer Science and Business Media LLC, 1996-12-01)
We have used a low noise Scanning Hall Probe Microscope (SHPM) to study vortex structures in superconducting films. The microscope has high magnetic field (similar to 2.9 x 10(-8)T/root Hz at 77 K) and spatial resolution, similar to 0.85 mu m. Magnetic field profiles of single vortices in High T-c YBa2Cu3O7-delta thin films have been successfully measured and the microscopic penetration depth of the superconductor has been extracted as a function of temperature. Flux penetration into the superconductor has ...
Bean-Livingston surface barriers for flux penetration in Bi2Sr2CaCu2O8+delta single crystals near the transition temperature
Mihalache, V.; Dede, M.; Oral, Ahmet; Miu, L. (2011-10-01)
The first field for magnetic flux penetration H in Bi2Sr2CaCu2O8+delta (Bi-2212) single crystals near the critical temperature T-c was investigated from the local magnetic hysteresis loops registered for different magnetic field H sweeping rates by using a scanning Hall probe microscope (SHPM) with similar to 1 mu m effective spatial resolution. Evidences for a significant role of the surface barrier were obtained: the asymmetric shape of the magnetization loops and an anomalous change in the slope of H-p(T...
Citation Formats
A. Oral, S. Ooi, H. Taoka, T. Tamegai, and M. Henini, “Disorder-driven intermediate state in the lattice melting transition of Bi2Sr2CaCu2O8+delta single crystals,” PHYSICAL REVIEW B, vol. 56, no. 22, pp. 14295–14298, 1997, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/94501.