The study on temperature dependent superfluid density of anisotropic superconductors

A self-consistent two-gap γ -model is used to quantitatively describe several thermodynamic properties of MgB 2 superconductor. The superconducting coupling matrix, ν i j , was obtained from the fitting of the superfluid density in the entire superconducting temperature range. Using this input, temperature-dependent superconducting gaps, specific heat, and upper critical fields were calculated with no adjustable parameters and compared with the experimental data as well as with the first-principles calculations. The observed agreement between fit and data shows that γ -model provides adequate quantitative description of the two-gap superconductivity in MgB 2 and may serve as a relatively simple and versatile self-consistent description of the thermodynamic quantities in multi-gap superconductors.

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Structures of vortex in Co-doped BaFe2As2 iron superconductors with different doping level by scanning Hall probe microscopy

Tikrit Journal of Pure Science ◽

10.25130/j.v22i11.720 ◽

2018 ◽

Vol 22 (11) ◽

pp. 55

Author(s):

Hussein Ali Mohammed

Keyword(s):

Superfluid Density ◽

Hall Probe ◽

Temperature Dependent ◽

Probe Microscopy ◽

New Class ◽

Iron Based ◽

Iron Superconductors ◽

Scanning Hall Probe Microscopy ◽

Suitable Technique ◽

Co Doped

The 122 iron arsenide unconventional superconductors are part of a new class of iron-based superconductors. Co-doped BaFe2xCoxAs2 (Ba-122) iron superconductors sample have been examine by scanning Hall probe microscopy (SHPM) technique to find out the magnetic properties of Ba-122 . Has been completed the evolution of profiles of vortices which has well isolated and it is as function of temperature, then utilized suitable technique to extract the temperature depending on penetration depth, .So, this allowed to deduce the temperature dependent on density of superfluid and it has been compared with α-model consequences for a (2-band) of superconductor. When the superfluid density for the BaFe2xCoxAs2 (Over D x= 0.113) sample. As result, the two gap -model has been fitted to the data with Δ1=4.25kTc, Δ2=1.92kTc , =0.708, 1=0.293 then a2=1. However, When values of for the BaFe2-xCoxAs2 (Over D x= 0.075) sample. Result of the superfluid density for BaFe2-xCoxAs2 with parameters are (Δ1=3.9k, Δ2=1.6k), =0.615 for Δ1, and =0.237, =1. Suitable parameters produce refer into the symmetry of the order parameter at hole pockets with the electron, and then the relative supports of the bands to the density of superfluid in the iron-based crystals.

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DOPING DEPENDENT FLUCTUATIONS NEAR Tc IN THE BI2212 SUPERCONDUCTOR

International Journal of Modern Physics B ◽

10.1142/s0217979200003022 ◽

2000 ◽

Vol 14 (25n27) ◽

pp. 2872-2877

Author(s):

D. DI CASTRO ◽

N. L. SAINI ◽

A. BIANCONI ◽

A. LANZARA

Keyword(s):

Electronic Structure ◽

Intimate Relationship ◽

Superfluid Density ◽

The Other ◽

Complex Conductivity ◽

Measured Temperature ◽

Temperature Dependent ◽

Exponential Increase ◽

Single Coil ◽

Superconducting Fluctuations

We have measured temperature dependent complex conductivity on Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212) superconducting system at different doping using single coil technique to determine the superconducting fluctuations near the T c . The results show that the fluctuation region below T c evolves linearly with the doping and is mainly controlled by the superfluid density. On the other hand, the fluctuation region above T c shows an exponential increase with underdoping and seems to have an intimate relationship with the anomalous electronic structure in the underdoped regime.

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(111) Monocrystalline Nickel Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100095819 ◽

1972 ◽

Vol 30 ◽

pp. 512-513

Author(s):

T.E. Pratt ◽

R.W. Vook

Keyword(s):

Film Thickness ◽

Deposition Rate ◽

Room Temperature ◽

Narrow Range ◽

High Vacuum ◽

Residual Pressure ◽

Temperature Dependent ◽

Deposition Parameters ◽

Transmission Electron ◽

Substrate Temperatures

(111) oriented thin monocrystalline Ni films have been prepared by vacuum evaporation and examined by transmission electron microscopy and electron diffraction. In high vacuum, at room temperature, a layer of NaCl was first evaporated onto a freshly air-cleaved muscovite substrate clamped to a copper block with attached heater and thermocouple. Then, at various substrate temperatures, with other parameters held within a narrow range, Ni was evaporated from a tungsten filament. It had been shown previously that similar procedures would yield monocrystalline films of CU, Ag, and Au.For the films examined with respect to temperature dependent effects, typical deposition parameters were: Ni film thickness, 500-800 A; Ni deposition rate, 10 A/sec.; residual pressure, 10-6 torr; NaCl film thickness, 250 A; and NaCl deposition rate, 10 A/sec. Some additional evaporations involved higher deposition rates and lower film thicknesses.Monocrystalline films were obtained with substrate temperatures above 500° C. Below 450° C, the films were polycrystalline with a strong (111) preferred orientation.

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