Impurity effects on the superconducting coherence length in Zn- or Ni-dopedYBa2Cu3O6.9single crystals

1999 ◽  
Vol 60 (1) ◽  
pp. 114-117 ◽  
Author(s):  
K. Tomimoto ◽  
I. Terasaki ◽  
A. I. Rykov ◽  
T. Mimura ◽  
S. Tajima
Keyword(s):  
Coherence Length ◽  
Impurity Effects ◽  
Superconducting Coherence Length

scholarly journals Superconducting coherence length of hole-doped cuprates obtained from electron–boson spectral density function

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jungseek Hwang
Keyword(s):  
Spectral Density ◽  
Coherence Length ◽  
Cooper Pair ◽  
Average Frequency ◽  
Spin Fluctuations ◽  
Fermi Velocity ◽  
Cooper Pairs ◽  
Spectroscopic Techniques ◽  
Microscopic Mechanism ◽  
Superconducting Coherence Length

AbstractElectron–boson spectral density functions (EBSDFs) can be obtained from measured spectra using various spectroscopic techniques, including optical spectroscopy. EBSDFs, known as glue functions, are suggested to have a magnetic origin. Here, we investigated EBSDFs obtained from the measured optical spectra of hole-doped cuprates with wide doping levels, from underdoped to overdoped cuprates. The average frequency of an EBSDF provides the timescale for the spin fluctuations to form Cooper pairs. This timescale is directly associated with retarded interactions between electrons. Using this timescale and Fermi velocity, a reasonable superconducting coherence length, which reflects the size of the Cooper pair, can be extracted. The obtained coherence lengths were consistent with those measured via other experimental techniques. Therefore, the formation of Cooper pairs in cuprates can be explained by spin fluctuations, the timescales of which appear in EBSDFs. Consequently, EBSDFs provide crucial information on the timescale of the microscopic mechanism of Cooper pair formation.

Fabrication and Electric Transport in MgB2 Doped with Nanosized Carbon-Based Core-Shell Structures

2010 ◽  
Vol 663-665 ◽  
pp. 871-875
Author(s):  
Viorel Sandu ◽  
Gheorghe Virgil Aldica ◽  
Stelian Popa ◽  
Elena Cimpoiasu ◽  
Florian Dumitrache ◽  
...  
Keyword(s):  
Coherence Length ◽  
Shell Structures ◽  
Electric Transport ◽  
Metallic Core ◽  
The Core ◽  
Ceramic Samples ◽  
Plasma Sintering ◽  
Short Processing Time ◽  
Spark Plasma ◽  
Superconducting Coherence Length

We present the fabrication and electric properties of MgB2 ceramic samples doped with nanosized spheres, 4-8 nm, of graphite with a metallic core. The samples were prepared using the spark plasma sintering technique. The size of the additive is comparable to the superconducting coherence length. The short processing time limits the diffusion of the carbon while keeping the core intact. Therefore, in addition to the doping with carbon, the metallic core, which has the size smaller than the superconducting coherence length, create pinning centers which might improve the dissipationless electric transport. The results are analyzed in the framework of different pinning models.

scholarly journals Superconducting Coherence Length of Hole-doped Cuprates Obtained From Electron-boson Spectral Density Function

2021 ◽  
Author(s):  
Jungseek Hwang
Keyword(s):  
Spectral Density ◽  
Coherence Length ◽  
Cooper Pair ◽  
Average Frequency ◽  
Spin Fluctuations ◽  
Fermi Velocity ◽  
Cooper Pairs ◽  
Spectroscopic Techniques ◽  
Microscopic Mechanism ◽  
Superconducting Coherence Length

Abstract Electron{boson spectral density functions (EBSDFs) can be obtained from measured spectra using various spectroscopic techniques, including optical spectroscopy. EBSDFs, known as glue functions, have a magnetic origin. Here, we investigated EBSDFs obtained from the measured optical spectra of hole-doped cuprates with wide doping levels, from underdoped to overdoped cuprates. The average frequency of an EBSDF provides the timescale for the spin fluctuations to form Cooper pairs. This timescale is directly associated with retarded interactions betweenelectrons. Using this timescale and Fermi velocity, a reasonable superconducting coherence length, which reflects the size of the Cooper pair, can be extracted. The obtained coherence lengths were consistent with those measured via other experimental techniques. Therefore, the formation of Cooper pairs in cuprates can be explained by spin fluctuations, the timescales of which appear in EBSDFs. Consequently, EBSDFs provide crucial information on the timescale of the microscopic mechanism of Cooper pair formation.

SCALING BETWEEN LOCALIZATION LENGTH AND TC IN DISORDERED YBa2Cu3O6.9

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3601-3604
Author(s):  
ANDREA GAUZZI ◽  
DAVOR PAVUNA
Keyword(s):  
Coherence Length ◽  
Localization Length ◽  
Charge Carriers ◽  
Superconducting Transition ◽  
Scaling Relation ◽  
X Ray Diffraction ◽  
Ginzburg Landau ◽  
X Ray ◽  
Structural Coherence ◽  
Superconducting Coherence Length

We quantitatively study the effect of growth-induced reduction of long range structural order on the superconducting transition in epitaxial YBa 2 Cu 3 O 6.9 films. The corresponding reduction of structural coherence length rc is determined from the width of X-ray diffraction rocking curves. Tc measurements in the films give evidence for the validity of the empirical scaling relation ΔTc~ rc,ab-2, where ΔTc is the disorder-induced reduction of Tc and rc,ab is the structural coherence length in the ab-plane. To explain this algebraic law we propose a simple phenomenological model based on the disorder-induced localization of the charge carriers within each ordered domain of size rc,ab. This picture enables us to precisely determine the Ginzburg-Landau superconducting coherence length in the ab-plane, and we obtain ξab=1.41±0.04 nm.

BCS-Bose theory of the superconducting coherence length

1995 ◽  
Vol 94 (6) ◽  
pp. 419-423 ◽  
Author(s):  
M. Casas ◽  
J.M. Getino ◽  
M. de Llano ◽  
A. Puente ◽  
R.M. Quick ◽  
...  
Keyword(s):  
Coherence Length ◽  
Superconducting Coherence Length

Local order in YBa2Cu3−yCoyO6+2x studied by anomalous diffuse x-ray scattering

1994 ◽  
Vol 9 (12) ◽  
pp. 3050-3058 ◽  
Author(s):  
H. Renevier ◽  
X.B. Kan ◽  
J.P. Quintana ◽  
K.J. Zhang ◽  
J.B. Cohen
Keyword(s):  
Coherence Length ◽  
Local Order ◽  
X Ray ◽  
Intensity Measurements ◽  
X Ray Scattering ◽  
Co Concentration ◽  
Structural Coherence ◽  
Superconducting Coherence Length ◽  
The Difference ◽  
Ray Scattering

The local order in a single crystal of YBa2Cu2.53Co0.47O7.13 has been studied with anomalous diffuse x-ray scattering. (For such a Co concentration the compound is nonsuperconducting.) Intensity measurements were carried out at two energies below the Co edge. The difference data could then be expressed in terms of the local structure around a Co atom. The short-range order parameters (α's) indicate that the Co and Cu atoms are nearly randomly distributed on the Cu1 sites. The estimated size of the Co-free “domains” is 5-7 Å. The first neighbor in-plane Co-Co distances are significantly shortened, indicating that the Co atoms are displaced from their average positions. The data also show a significant decrease of the Co-O1 distance, leading to an increase of the Cu2-O1 distance. The lengthening of the Cu2-O1 distance implies a lowering of the Cu2 formal valence. The Co substitution also affects the in-plane Cu2 positions. The present study shows that the Cu-O2 structural coherence is altered on a scale smaller than the superconducting coherence length. As far as the superconductivity is concerned, the Cu2 valence remains one of the most important parameters in determining the superconducting properties of the Co-doped 123 compounds. On the other hand, there is some evidence that in order for superconductivity to occur in this and other doped cuprate compounds, the size of dopant-free regions in the basal plane may have to exceed the superconducting coherence length.

Single-Mode Superconductivity in LaAlO3/SrTiO3 Nanostructures

2013 ◽  
Vol 1507 ◽  
Author(s):  
Joshua P. Veazey ◽  
Guanglei Cheng ◽  
Patrick Irvin ◽  
Shicheng Lu ◽  
Mengchen Huang ◽  
...  
Keyword(s):  
Cross Sections ◽  
Quantum Channel ◽  
Coherence Length ◽  
Single Mode ◽  
Two Dimensional ◽  
Single Quantum ◽  
Fundamental Interest ◽  
Atomic Force ◽  
Superconducting Coherence Length ◽  
Properties Of Superconductors

ABSTRACTThe properties of superconductors at the extreme limits of dimensionality are of fundamental interest. The interface of LaAlO3 and SrTiO3 hosts a quasi-two-dimensional superconductor below Tc≈200 mK. Here we report superconductivity in nanowire-shaped structures created at the LaAlO3/SrTiO3 interface using conductive atomic force microscope lithography. Nanowire cross-sections are small compared to the superconducting coherence length in LaAlO3/SrTiO3 (w <<ξSC∼100 nm), placing them in the quasi-1D regime. The ability to “write” fully superconducting nanostructures on an insulating LaAlO3/SrTiO3 “canvas” opens possibilities for the development of new families of superconducting nanoelectronics. Four-terminal transport measurements suggest that in some devices both the normal and superconducting states are confined to a single quantum channel.

scholarly journals Measuring the superconducting coherence length in thin films using a two-coil experiment

2013 ◽  
Vol 88 (13) ◽  
Author(s):  
John Draskovic ◽  
Thomas R. Lemberger ◽  
Brian Peters ◽  
Fengyuan Yang ◽  
Jaseung Ku ◽  
...  
Keyword(s):  
Thin Films ◽  
Coherence Length ◽  
Superconducting Coherence Length
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