ANALYSIS OF MAGNETIC CRITICAL FIELDS IN IRON-BASED SmFeAsO0.85 HIGH-Tc SUPERCONDUCTOR

2011 ◽  
Vol 25 (24) ◽  
pp. 1939-1948 ◽  
Author(s):  
DAWOOD AHMAD ◽  
TAE KWON SONG ◽  
IN SUK PARK ◽  
G. C. KIM ◽  
ZHI-AN REN ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Low Temperatures ◽  
Irreversibility Line ◽  
Linear Temperature Dependence ◽  
Critical Fields ◽  
Linear Temperature ◽  
High Tc ◽  
High Tc Superconductor ◽  
Pressure Synthesis ◽  
Iron Based

The magnetic properties of the newly discovered iron-oxypnictide SmFeAsO 0.85 high-Tc superconductor with a Tc of around 55 K were investigated. Bulk SmFeAsO 0.85 was prepared by a method for high-pressure synthesis. The lower critical field H c1 was estimated from the magnetization at low fields; H c1 (0) was measured to be 212 Oe. A linear temperature dependence instead of saturation at low temperatures in H c1 (T) revealed unconventional superconductivity with a nodal gap structure in our SmFeAsO 0.85 superconductor. The results showed that the well-known secondary peak in the temperature dependence of the critical current density Jc is absent in the SmFeAsO 0.85 high-Tc superconductor. The irreversibility line B irr was fitted well by the power law dependence (1 - T/Tc)n with n ~ 1.5. This is indicative of the flux creep phenomena in the SmFeAsO 0.85 high-Tc superconductor. In addition, within the range of measurement temperatures in this study, no crossover was observed in the temperature dependence of the irreversibility line B irr which may be due to low anisotropy in our SmFeAsO 0.85 superconductor.

scholarly journals Linear temperature dependence of resistivity and change in the Fermi surface at the pseudogap critical point of a high-Tc superconductor

2008 ◽  
Vol 5 (1) ◽  
pp. 31-34 ◽  
Author(s):  
R. Daou ◽  
Nicolas Doiron-Leyraud ◽  
David LeBoeuf ◽  
S. Y. Li ◽  
Francis Laliberté ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Temperature Dependence ◽  
Critical Point ◽  
Linear Temperature Dependence ◽  
Linear Temperature ◽  
High Tc ◽  
High Tc Superconductor

MICROWAVE ABSORPTION STUDIES ON HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS X—ESR OF Gd IN Y-Ba-Cu-O BETWEEN ABOUT Tcand 600°C

1992 ◽  
Vol 06 (24) ◽  
pp. 1525-1530 ◽  
Author(s):  
K. SUGAWARA ◽  
S. TANAKA
Keyword(s):  
Temperature Gradient ◽  
Temperature Dependence ◽  
Inhomogeneous Magnetic Field ◽  
Linear Temperature Dependence ◽  
High Temperature Side ◽  
Linear Temperature ◽  
High Tc ◽  
Absorption Studies ◽  
Zero Resistance ◽  
Temperature Side

Temperature dependence of ESR linewidth, ΔHPP, of Gd3+ in Y1−xGdxBa2Cu3Oy (x=0.2, 0.5 and 1) has been studied between about Tc (zero-resistance temperature) and about 600°C. For all the samples, ΔHPP progressively broadens as temperature approaches Tc from high temperature side, presumably due to inhomogeneous magnetic field distributions arising from superconductivity. On the contrary, ΔHpp is nearly linear in temperature between about 100 K and 600 K with temperature gradient, ∂(ΔHPP)/∂T~0.6 G/deg. The linear temperature dependence is assumed to be due to the Korringa relation. From the temperature gradient obtained above, JN(EF) was estimated as 0.0025, where J is the coupling coefficient between Gd spin S and conduction carrier’s spin S, and N(EF) is the density of states on the Fermi surface. In addition, by substituting an appropriate value for J, N(EF) was crudely estimated for the Y-Gd-Ba-Cu-O system.

Irreversibility line and flux pinning properties in iron-based high-Tc superconductor SmFeAsO0.85

2009 ◽  
Vol 469 (15-20) ◽  
pp. 1052-1054 ◽  
Author(s):  
D. Ahmad ◽  
I. Park ◽  
G.C. Kim ◽  
J.H. Lee ◽  
Z.-A. Ren ◽  
...  
Keyword(s):  
Flux Pinning ◽  
Irreversibility Line ◽  
High Tc ◽  
High Tc Superconductor ◽  
Iron Based ◽  
Pinning Properties

DOPING AND TEMPERATURE DEPENDENCE OF SUPERFLUID DENSITY IN KINETIC ENERGY DRIVEN CUPRATE SUPERCONDUCTORS

2010 ◽  
Vol 24 (29) ◽  
pp. 2845-2854
Author(s):  
ZHEYU HUANG ◽  
HUAISONG ZHAO ◽  
SHIPING FENG
Keyword(s):  
Transition Temperature ◽  
Kinetic Energy ◽  
Temperature Dependence ◽  
Low Temperatures ◽  
Cuprate Superconductors ◽  
Superfluid Density ◽  
Linear Temperature Dependence ◽  
Superconducting Transition ◽  
Zero Temperature ◽  
Linear Temperature

Within the kinetic energy driven superconducting mechanism, the doping and temperature dependence of the superfluid density in cuprate superconductors is studied throughout the superconducting dome. It is shown that the superfluid density shows a crossover from the linear temperature dependence at low temperatures to a nonlinear one in the extremely low temperatures. In analogy to the dome-like shape of the doping dependent superconducting transition temperature, the maximal zero-temperature superfluid density occurs around the critical doping δ ≈ 0.195, and then decreases in both lower doped and higher doped regimes.

DYNAMICS OF TWIN BOUNDARIES AND HIGH Tc SUPERCONDUCTORS

1987 ◽  
Vol 01 (03n04) ◽  
pp. 931-940
Author(s):  
B. Horovitz ◽  
G.R. Barsch ◽  
J.A. Krumhansl
Keyword(s):  
Specific Heat ◽  
Temperature Dependence ◽  
Electronic Properties ◽  
Twin Boundary ◽  
Linear Temperature Dependence ◽  
High Tc Superconductors ◽  
Linear Temperature ◽  
High Tc ◽  
Vertex Corrections ◽  
Anisotropic Dispersion

The formation of coherent arrays of twins in a tetragonal to orthorhombic transition and its effects on electronic properties are studied. The twin boundary oscillations (“dyadons”) have an anisotropic dispersion with frequencies typically ≲1010 sec −1 for wavevectors perpendicular to the boundaries. This results in a ~T2 contribution to the specific heat for T≳ 1° K and a linear temperature dependence of the resistivity. The unusual anisotropy yields vertex corrections which diverge at high temperatures and can enhance T c.

NANOSCOPIC PHASE SEPARATION AND THE UNIVERSAL TRANSPORT AND MAGNETIC PROPERTIES OF HIGH Tc SUPERCONDUCTORS

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3528-3531
Author(s):  
J. JUNG ◽  
H. YAN ◽  
H. DARHMAOUI ◽  
M. ABDELHADI
Keyword(s):  
Magnetic Properties ◽  
Phase Separation ◽  
Temperature Dependence ◽  
Current Density ◽  
Low Temperatures ◽  
Energy Barrier ◽  
Vortex Motion ◽  
Superfluid Density ◽  
High Tc Superconductors ◽  
High Tc

We have found the correlation between nanoscopic phase separation in the copper-oxygen planes of YBCO and TlBCCO and the transport and magnetic properties of these materials in the a-b planes such as: the temperature dependence of the critical current density Jc( T ), the temperature dependence of the superfluid density ns( T )∝1/λ2( T ) at low temperatures, the temperature dependence of the normalized logarithmic relaxation rate S(T), and the dependence of the effective energy barrier against vortex motion on the current density Ueff( J ). These properties are controlled by the ratio of the amount of an underdoped filamentary phase to that of an optimally doped one.

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