Thermal expansion and spin gap in the normal state of YBa2Cu3Oy with La doping and oxygen-deficiency

2004 ◽  
Vol 402 (1-2) ◽  
pp. 88-93 ◽  
Author(s):  
X.S. Wu ◽  
H.L. Cai ◽  
Y.M. Xu ◽  
W.S. Tan ◽  
A. Hu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Normal State ◽  
Oxygen Deficiency ◽  
Spin Gap ◽  
La Doping

THE STUDY ON THE SPIN GAP PHENOMENON IN OXYGEN DEFICIENT YBa2Cu3O6+δ AND Ca-DOPED Y1-xCaxBa2Cu3O6+δ SUPERCONDUCTORS

1999 ◽  
Vol 13 (27) ◽  
pp. 3219-3234 ◽  
Author(s):  
L. J. SHEN ◽  
C. C. LAM ◽  
X. JIN ◽  
H. S. LAM ◽  
S. H. LI
Keyword(s):  
High Temperature ◽  
Normal State ◽  
High Temperature Superconductivity ◽  
Oxygen Deficiency ◽  
High Temperature Superconductors ◽  
Pressure Effects ◽  
Thermal Excitation ◽  
Metallic State ◽  
Specific Function ◽  
Spin Gap

The understanding of the spin gap phenomenon in the normal state of the high temperature superconductors can provide the mechanism of the high temperature superconductivity. A specific function of thermal excitation for quasiparticles was introduced based on the experimental relationship between resistivity and temperature. This specific function describes the deviation in resistivity from the T-linear relationship w.r.t. the normal state of the high temperature superconductors. With this function, the spin gap is naturally introduced. Our experimental results indicate that the spin gap behavior is closely related not only to the oxygen deficiency but also to the structural change in the a–b plane. Furthermore, we found that the crossover from anomalous metallic state to spin gap state takes place within a temperature range T S <T<T*, which depends on the oxygen content and the Ca-doping level. Pressure effects on the spin gap phenomenon in bulk samples of oxygen-deficient YBa 2 Cu 3 O 6+δ and Ca-doped Y 1-x Ca x Ba 2 Cu 3 O 6+δ were also investigated. Under high hydrostatic pressure the spin gap behavior is also severely influenced by the contraction of the a–b plane due to the pressure.

Anomaly in Thermal Expansion of YB2Cu307-y Around 250K

1989 ◽  
Vol 169 ◽  
Author(s):  
G.A. Ramadass ◽  
V. Ramcahdnran ◽  
R. Srinivasan
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Linear Thermal Expansion Coefficient ◽  
Oxygen Deficiency ◽  
Linear Thermal Expansion

AbstractThe linear thermal expansion coefficient of YBa2Cu307 as a function of temperature has been studied. An anomaly is observed at 250K. This temperature is found to be dependent on oxygen deficiency.

THE NORMAL STATE HALL EFFECT IN NdBa2-xLaxCu3O7-δ: EVIDENCE FOR HOLE LOCALIZATION BY LA DOPING

2009 ◽  
Vol 23 (31) ◽  
pp. 5779-5788
Author(s):  
S. R. GHORBANI ◽  
F. ABRINAEY
Keyword(s):  
Critical Temperature ◽  
Hall Effect ◽  
Hall Coefficient ◽  
Normal State ◽  
Doping Concentration ◽  
Narrow Band ◽  
Band Model ◽  
Measured Temperature ◽  
Temperature Range ◽  
La Doping

The transport properties of sintered samples of NdBa 2-x La x Cu 3 O 7-δ with 0 ≤ x ≤ 0.3 have been studied in the normal state by Hall effect measurements. The Hall coefficient, RH is positive in the normal state and increases with increasing La doping concentration over the whole temperature range from the critical temperature, Tc, up to room temperature. The results for the Hall coefficient as a function of temperature and doping concentration were analyzed within the phenomenological narrow band and Anderson models. A good agreement between models and data was obtained. As in the phenomenological narrow band model, the band widths increase with increasing doping concentration. As in the Anderson model, the Hall angle is proportional to T2 over the whole measured temperature range for all samples. The obtained results for both models supported the view that La doping introduces electronic disorder into the CuO 2 planes. The tendency towards localization is driven by electronic disorder. In addition to hole filling, the localization is another reason for the decreasing superconducting critical temperature in these samples.

scholarly journals Paramagnetic Resonance as a Probe of the Spin Gap in Normal State of Superconductor

2011 ◽  
Vol 2011 ◽  
pp. 1-3
Author(s):  
Frank J. Owens
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Transition Temperature ◽  
Normal State ◽  
Oxide Superconductors ◽  
Superconducting Transition ◽  
Paramagnetic Resonance ◽  
Spin Gap ◽  
Order Of Magnitude ◽  
Copper Oxide Superconductors ◽  
Electron Paramagnetic

It is shown that electron paramagnetic resonance (EPR) can be used to observe the spin gap in copper oxide superconductors. The electron paramagnetic resonance spectra of the Cu2+ ion in underdoped show a pronounced decrease in intensity in the normal state as the temperature is lowered to 133 K, the superconducting transition temperature of the material. The decrease is attributed to a pairing of the Cu2+   spins to form a spin gap. A spin gap of 0.0533 eV is estimated from the data which is in order of magnitude agreement with values obtained from NMR measurements.

Fe-excess Ions as Electronic Charge Suppliers for Zero Thermal Expansion in the Normal State of Fe1.16Te0.6Se0.4

2015 ◽  
Vol 84 (9) ◽  
pp. 094713
Author(s):  
Sunil K. Karna ◽  
Chi-Hung Lee ◽  
Wen-Hsien Li ◽  
Raman Sankar ◽  
Fang-Cheng Chou ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Normal State ◽  
Electronic Charge ◽  
Fe Excess

Normal state spin gap of Bi-based superconductors

1997 ◽  
Vol 282-287 ◽  
pp. 1003-1004
Author(s):  
Z.-Q. Mao ◽  
G.-J. Xu ◽  
R.-P. Wang ◽  
K.-Q. Wang ◽  
M.-L. Tian ◽  
...  
Keyword(s):  
Normal State ◽  
Spin Gap ◽  
State Spin

Spin Gap, Electronic Crossover, and Charge Density Waves in Y-Ba-Cu-O Superconductors

1998 ◽  
Vol 53 (6-7) ◽  
pp. 488-491
Author(s):  
Detlef Brinkmann
Keyword(s):  
Charge Density ◽  
Normal State ◽  
Density Wave ◽  
Charge Density Waves ◽  
Gap Effect ◽  
Spin Excitation ◽  
Nmr Studies ◽  
Spin Gap ◽  
A Charge ◽  
University Of Zurich

Abstract This paper discusses recent NQR/NMR studies performed on Y-Ba-Cu-0 superconductors at the University of Zürich. The work is concerned with normal state properties which are still controversial, for instance the spin-gap effect, i.e. the opening of a pseudo gap in the electron spin excitation spectrum at a temperature T*, which lies above Tc . We will report on the detection of “anomalies” which are dis-played in the temperature dependence of several NMR and NQR quantities measured in the normal state of YBa2Cu4O8 . These anomalies are interpreted as an electronic crossover which involves a charge re-distribution in the CuO2 planes and an enhancement of the charge fluctuations. As a possible mechanism of the crossover, a charge density wave instability is proposed.

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