Search results for "laser"

Macroscopic persistent currents in laser deposited YBa2Cu3O7 films

1989

We have investigated persistent currents in a superconducting YBa2Cu3O7 ring of about 1 cm diameter, which was deposited as c-axis textured film on a SrTiO3 substrate by laser ablation. The currents were registered, via their magnetic field distribution, with a small vibrating pick-up coil. At 77 K persistent currents with negligible decay over 103 s have been observed below a critical current density jc=0.9×105 A/cm2, both for a field-cooled and a zero-field-cooled sample. This demonstrates that it is possible to fabricate dissipationless devices of such films on a relatively large scale.

Resistivity and irreversibility line of (Hg0.9Re0.1)Ba2CaCu2O6+δ HTS thin films

2003

Abstract High-quality epitaxial (Hg 0.9 Re 0.1 )Ba 2 CaCu 2 O 6+ δ HTS thin films were successfully prepared by pulsed laser deposition (PLD) of Hg-free precursor material on (1 0 0)-oriented SrTiO 3 substrates with subsequent Hg vapour annealing. (Hg 0.9 Re 0.1 )Ba 2 CaCu 2 O 6+ δ HTS thin films exhibit sharp superconducting transitions at T c ≈122 K. The electrical resistance for c -axis oriented HgRe-1212 films has been studied as a function of temperature and dc magnetic fields up to 10 T parallel to the crystallographic c -axis. The irreversibility line for the HgRe-1212 has been deduced from the data and investigated as a function of reduced temperature T / T c . The result of the irr…

Normal and mixed state Hall effect in (Hg0.9Re0.1)Ba2CaCu2O6+δ fully textured HTSC thin films

2004

Abstract Temperature and magnetic field dependence of the Hall effect in the normal and mixed state of fully textured (Hg0.9Re0.1)Ba2CaCu2O6+δ (HgRe-1212) HTSC thin films prepared by laser ablation deposition have been studied. The longitudinal resistivity ρxx and Hall resistivity ρyx of HgRe-1212 superconductor thin films were measured for a wide range of magnetic fields from 125 mT to 12 T with the field perpendicular to the ab plane and the current in the ab plane. A sign change of the Hall resistivity is observed in fields below 3 T in the region close to the superconducting onset temperature. The temperature dependencies ρxx ∝ T and ρyx ∝ 1/T have been observed for HgRe-1212 thin films…

Laser floating zone growth of textured Ag/(Bi,Pb)SrCaCuO superconductors

1992

Influence of micro-structure in the low temperature critical currents of YBa2Cu3O7?? thin films

1996

Epitaxial YBa2Cu3O7−δ films nucleate in c-axis oriented single-crystalline islands. The surface of the single-crystalline SrTiO3 substrates exhibit steps of one third of the YBa2Cu3O7−δ c-axis. These steps generate a mismatch in the island boundaries between the CuO2 superconducting blocks. We show that these defect regions are strong candidates for being the pinning centers responsible for the large critical currents observed in Laser Ablated and Sputtered thin films.

Macroscopic persistent currents in laser ablated YBa2Cu3O7-x films

2011

AbstractThin films of YBa2Cu3O7-x have been produced in situ by laser ablation. As the condensation of the superconducting film is done onto hot substrates (600 - 780°C) at high oxygen pressures (~ 1 mbar), this techniques does not require any special postannealing step. Thus the total process time amounts to less than 10 min. Films were found to be polycrystalline with the c-axis preferentially oriented normal to the substrate plane on single crystalline (001) SrTiO3 and (random) ZrO2, as measured by ion channeling (Xmin = 5.5 % on SrTiO3), x-ray scattering and TEM. Complete superconducting transitions above 90 K with transition widths of about 1 K have been observed even on YSZ substrates…

Investigation of the epitaxy of thin YBa2Cu3O7-delta films

1990

Abstract The degree of epitaxy of thin sputtered and laser ablated films have been investigated by Raman spectroscopy. Using the selection rules for Raman scattering for the different phonons in YBa 2 Cu 3 O 7−δ the superconducting films on SrTiO 3 and MgO are found to be epitaxially grown with the c -axis perpendicular to the substrate. On ZrO 2 the films also grow with their c -axis perpendicular to the substrate, but with randomly oriented a / b -directions in the plane of the film.

High quality superconducting titanium nitride thin film growth using infrared pulsed laser deposition

2018

Transport and Diamagnetic Properties of 2:2:1:2 and 2:2:2:3 (Bi-Pb)-Sr-Ca-Cu-O Superconducting Materials

1989

AbstractBismuth superconducting oriented fibers of the compositions 2:2:1:2: and 2:2:2:3 have been grown by the Laser Floating Zone (LFZ) method. Growth conditions have been optimized in order to improve the superconducting properties. The 108 K onset in susceptibility measurements (associated to the 2:2:2:3 phase) only appears well defined when starting from Sr-defective precursors.

Landau damping in high-temperature superconductors

1995

We investigate the decay of a phonon into single-electron excitations in the cuprate superconductors. In a clean crystal the screening of the longitudinal phonon field cancels singularity of the Landau damping threshold and makes it experimentally unobservable. In a dirty metal the phase volume of the electrons involved in damping is small, which reduces the probability of the phonon decay. However, in this case the observation of dependence between the phonon linewidth and light penetration depth is more favorable than in the clean metal because the damping has no threshold.