RESISTIVE UPPER CRITICAL FIELD OF SUPERCONDUCTING SPIN-LADDER Sr14-xCaxCu24O41

2000 ◽  
Vol 14 (29n31) ◽  
pp. 3617-3622 ◽  
Author(s):  
T. NAKANISHI ◽  
N. MOTOYAMA ◽  
H. MITAMURA ◽  
N. TAKESHITA ◽  
H. TAKAHASHI ◽  
...  
Keyword(s):  
High Pressure ◽  
Critical Field ◽  
Pressure Range ◽  
Upper Critical Field ◽  
Anomalous Behavior ◽  
Spin Ladder ◽  
Two Dimensional ◽  
High Pressure Cell ◽  
Upward Curvature ◽  
Superconducting Oxides

We report the resistive upper critical field Hc2(T) of the hole-doped two-leg ladder Sr 14-x Ca x Cu 24 O 41(x=12) single crystal, which becomes superconducting with Tc~5 K in a pressure range above ~3.0 GPa . Using a newly developed compact high-pressure cell, the magneto-transport measurements have been performed at temperatures down to ~140 mK under high pressure above 3.5 GPa. It is found that Hc2 (perpendicular to the ladder Cu 2 O 3 plane) increases anomalously as the temperature is decreased having an upward curvature and shows no saturation down to T/T c ~ 0.03. Also, its temperature dependence is found to resemble that of the high-Tc superconducting oxide Tl 2 Ba 2 CuO 6. This fact suggests that the anomalous behavior of Hc2 has a common origin between the ladders and the two-dimensional high-Tc superconducting oxides.

Mean-field analysis on the magnetic properties of non-centrosymmetric superconductor LaNiC2

2018 ◽  
Vol 96 (2) ◽  
pp. 189-193
Author(s):  
Jia-Li Zhang
Keyword(s):  
Critical Field ◽  
Landau Theory ◽  
Theoretical Calculations ◽  
Mean Field ◽  
Upper Critical Field ◽  
Field Analysis ◽  
S Wave ◽  
Wave State ◽  
Ginzburg Landau ◽  
Upward Curvature

Based on two-band isotropic Ginzburg–Landau theory, we study the temperature dependence of upper critical field and London penetration depth for non-centrosymmetric superconductor LaNiC2. All the theoretical calculations fit the experimental data very well, especially the upward curvature of upper critical field near the critical temperature. Our results thus indicate that the two-gap scenario is better to account for the superconductivity of LaNiC2, and the Cooper pairs of this superconductor are in the conventional s-wave state.

Anisotropic Upper Critical Field of Single Crystal RNi2B2C (R = Y, Lu)

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3264-3266 ◽  
Author(s):  
A. C. Du Mar ◽  
K. D. D. Rathnayaka ◽  
D. G. Naugle ◽  
P. C. Canfield
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Critical Field ◽  
Upper Critical Field ◽  
Critical Fields ◽  
Linear Behavior ◽  
Upward Curvature

Measurements of the anisotropic upper critical field curves have been extended for YNi 2B2C and LuNi2B2C (T c = 15.6 K and 16.1 K, respectively). Measurements of R(T, H) were taken along the crystallographic directions of <100> and <110>. The resulting critical fields show an upward curvature near T c and a linear behavior at low temperature, which continues to below 2 K with little, if any, sign of saturation.

Anisotropy of the upper critical field of the spin-ladder Sr14−xCaxCu24O41

2001 ◽  
Vol 226-230 ◽  
pp. 449-451 ◽  
Author(s):  
T. Nakanishi ◽  
N. Motoyama ◽  
H. Mitamura ◽  
N. Takeshita ◽  
H. Takahashi ◽  
...  
Keyword(s):  
Critical Field ◽  
Upper Critical Field ◽  
Spin Ladder

Upper Critical Field in Electron-Doped Superconductor with Nonstoichiometric Disorder near Antiferromagnetic-Superconducting Phase Boundary

2014 ◽  
Vol 215 ◽  
pp. 77-82 ◽  
Author(s):  
Tatiana B. Charikova ◽  
Nina G. Shelushinina ◽  
German I. Harus ◽  
Denis S. Petukhov ◽  
Andrei A. Ivanov
Keyword(s):  
Phase Boundary ◽  
Critical Field ◽  
Upper Critical Field ◽  
Superconducting Phase ◽  
Spin Fluctuations ◽  
S Wave ◽  
Optimal Doping ◽  
Resistivity Method ◽  
Upward Curvature ◽  
Disorder Parameter

Using the resistivity method it was found that temperature dependence of the upper critical field for underdoped Nd1.86Ce0.14CuO4+δ have an anomalous upward curvature of Hc2(T) dependence and can be consistently explained by the two-band/two-gap model of a dirty superconductor. Near antiferromagnetic-superconducting phase boundary the critical temperature remains constant with the change of the disorder parameter and the slope of Bc2 increases with increasing of the disorder parameter. This behavior is completely different from dependencies for pure superconducting phase at optimal doping region. This difference may indicate the change of the type of the paring: from the predominance of the anisotropic s-wave component (may be due to unstable competition between antiferromagnetic (AF) and superconducting (SC) regions) in underdoped (x=0.14) region to the prevalence of d-wave part in optimal doped regions (x=0.15) because of residual spin fluctuations.

The Temperature of Berezinsky – Kosterlitz – Thouless Transition in Two-Dimensional Superconductor in an External Field

2014 ◽  
Vol 9 (3) ◽  
pp. 75-80
Author(s):  
Aleksandr Krinitsyn ◽  
Iliya Tikhomirov ◽  
Klimentiy Yugay
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
External Magnetic Field ◽  
External Field ◽  
Critical Field ◽  
Applied Magnetic Field ◽  
Coherence Length ◽  
Upper Critical Field ◽  
Two Dimensional ◽  
Calculated Temperature

The Method of Monte-Carlo calculated temperature of Berezinsky – Kosterlitz – Thouless transition in twodimensional superconductor 2nd type in the presence of an external magnetic field. It is shown that near the upper critical field filling cells with a size of ξ × ξ relation, where ξ – coherence length at a given temperature, corresponds to half. It is also shown that ТBKT decreases with increasing interaction between the vortices and antivortices and increase of the external applied magnetic field

FLUX PINNING MECHANISM IN NEW MgCNi3 SUPERCONDUCTOR

2005 ◽  
Vol 19 (01n03) ◽  
pp. 327-330
Author(s):  
M. H. FANG ◽  
J. H. YANG ◽  
H. Y. WAN ◽  
W. ZHANG ◽  
M. KATO ◽  
...  
Keyword(s):  
High Pressure ◽  
Critical Field ◽  
Flux Pinning ◽  
Upper Critical Field ◽  
Structural Defects ◽  
Pinning Force ◽  
Irreversibility Field ◽  
Pinning Mechanism ◽  
Lower Critical Field ◽  
Flux Lattice

The measurements of lower-critical-field Hc1(T), upper-critical-field Hc2(T) and the bulk pinning force Fp(H) were carried out for a superconductor MgCNi 3 sample with Tc=7.5K prepared under high pressure. The sample has a good extensibility. We conclude that the flux pinning at lower fields results from the intra-granular structural defects, such as dislocations, and the enhancement of bulk pinning force near the irreversibility field Hirr is due to the softening of the flux lattice.

Upper critical field of CeCu2Si2 at very high pressure

1998 ◽  
Vol 106 (9) ◽  
pp. 631-636 ◽  
Author(s):  
E. Vargoz ◽  
D. Jaccard ◽  
J.Y. Genoud ◽  
J.P. Brison ◽  
J. Flouquet
Keyword(s):  
High Pressure ◽  
Critical Field ◽  
Upper Critical Field ◽  
Very High
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