Carbon-13-carbon-13 double bond isotope effect for Tc and consequences regarding the superconducting pairing mechanism in .kappa.-(ET)2X superconductors

1992 ◽  
Vol 31 (16) ◽  
pp. 3346-3348 ◽  
Author(s):  
K. Douglas Carlson ◽  
Aravinda M. Kini ◽  
Richard A. Klemm ◽  
H. Hau Wang ◽  
Jack M. Williams ◽  
...  
Keyword(s):  
Double Bond ◽  
Isotope Effect ◽  
Pairing Mechanism ◽  
Superconducting Pairing

The central bond 13C=13C isotope effect for superconductivity in high-Tc .beta.*-(ET)2I3 and its implications regarding the superconducting pairing mechanism

1992 ◽  
Vol 114 (25) ◽  
pp. 10069-10071 ◽  
Author(s):  
K. Douglas Carlson ◽  
Jack M. Williams ◽  
Urs Geiser ◽  
Aravinda M. Kini ◽  
H. Hau Wang ◽  
...  
Keyword(s):  
Isotope Effect ◽  
Pairing Mechanism ◽  
High Tc ◽  
13C Isotope ◽  
Central Bond ◽  
Superconducting Pairing

Evidence for Phonon-Mediated Coupling in Superconducting Ba0.6K0.4BiO3

1989 ◽  
Vol 156 ◽  
Author(s):  
D. G. Hinks ◽  
B. Dabrowski ◽  
D. R. Richards ◽  
J. D. Jorgensen ◽  
Shiyou Pei ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Strong Coupling ◽  
Isotope Effect ◽  
Tunneling Spectroscopy ◽  
Superconducting Gap ◽  
Optical Phonons ◽  
Pairing Mechanism ◽  
Strongly Coupled ◽  
A Value ◽  
O Isotope

ABSTRACTSuperconducting Ba0.6K0.4BiO3, with a Tc of 30K, shows a large 18O isotope effect which indicates that phonons are involved in the pairing mechanism. Infrared reflectivity measurements indicate a value for the superconducting gap consistent with moderate coupling (2Δ/kTc = 3.5 ± 0.5). A mediating energy for pairing of about 40 meV would be required to obtain a Tc of 30K. Strong coupling of electrons by optical phonons (which are present in this material with energies up to 80 meV) could account for the observed transition temperature. Recent tunneling spectroscopy shows the presence of strongly coupled optical phonons in the 40 to 70 meV region, indicating that superconductivity in this material may be phonon mediated.

Large copper isotope effect in oxygen depletedYBa2Cu3Oy: Importance of Cu-dominated phonon modes in the pairing mechanism

1996 ◽  
Vol 54 (21) ◽  
pp. 14956-14959 ◽  
Author(s):  
Guo-meng Zhao ◽  
Vidula Kirtikar ◽  
K. K. Singh ◽  
A. P. B. Sinha ◽  
Donald E. Morris ◽  
...  
Keyword(s):  
Isotope Effect ◽  
Copper Isotope ◽  
Phonon Modes ◽  
Pairing Mechanism

scholarly journals Dichotomy in the T -linear resistivity in hole-doped cuprates

2011 ◽  
Vol 369 (1941) ◽  
pp. 1626-1639 ◽  
Author(s):  
N. E. Hussey ◽  
R. A. Cooper ◽  
Xiaofeng Xu ◽  
Y. Wang ◽  
I. Mouzopoulou ◽  
...  
Keyword(s):  
Normal State ◽  
Low Temperatures ◽  
Temperature Limit ◽  
Anomalous Scattering ◽  
Superconducting Transition ◽  
Pairing Mechanism ◽  
Marked Contrast ◽  
Superconducting Pairing ◽  
Loss Of Coherence ◽  
Doping Range

From analysis of the in-plane resistivity ρ ab ( T ) of La 2− x Sr x CuO 4 , we show that normal state transport in overdoped cuprates can be delineated into two regimes in which the electrical resistivity varies approximately linearly with temperature. In the low-temperature limit, the T -linear resistivity extends over a very wide doping range, in marked contrast to expectations from conventional quantum critical scenarios. The coefficient of this T -linear resistivity scales with the superconducting transition temperature T c , implying that the interaction causing this anomalous scattering is also associated with the superconducting pairing mechanism. At high temperatures, the coefficient of the T -linear resistivity is essentially doping independent beyond a critical doping p crit =0.19 at which the ratio of the two coefficients is maximal. Taking our cue from earlier thermodynamic and photoemission measurements, we conclude that the opening of the normal-state pseudogap at p crit is driven by the loss of coherence of anti-nodal quasi-particles at low temperatures.

Enzymic aromatization of deuterium labelled testosterone and androst-4-ene-3,17-dione

1981 ◽  
Vol 59 (19) ◽  
pp. 2809-2819 ◽  
Author(s):  
Herbert L. Holland ◽  
Gregg J. Taylor
Keyword(s):  
Double Bond ◽  
Isotope Effect ◽  
Nmr Spectra ◽  
Deuterium Nmr ◽  
Secondary Effects ◽  
Deuterium Isotope Effect ◽  
Oxidative Removal ◽  
Primary And Secondary Effects ◽  
Rate Limiting

The preparation and aromatization by human placental microsomes of androst-4-ene-3-ones labelled with deuterium at C-4, C-6α, C-6β, C-16, and C-19 is described. Deuterium nmr spectra are reported for these compounds and for a sample of a 1,2-dideuterated androst-4-ene-3-one; the latter is formed nonstereospecifically by reduction of the C-1(2) double bond of a Δ1,4-diene-3-one. Aromatization by placental microsomes occurs with retention of deuterium at C-4 and C-6, but with some loss from C-16. The aromatization of 19-d1 and 19,19,19-d3 steroids in the presence of 16,16-d2 steroids has been carried out to determine the deuterium isotope effect for the oxidative removal of C-19. The values obtained (kH/kD for 19-d1 = 2.3, kH/kD for 19,19, 19-d3 = 3.2) are a combination of primary and secondary effects, but suggest that oxidation at C-19 is a rate-limiting reaction of the biosynthetic sequence.The fungus Pellicularia filamentosa NRRL 2727, reported to hydroxylate androst-4-ene-3,17-dione at C-19, gave only the products of hydroxylation at C-11α, C-11β, and C-14.

scholarly journals Superconducting pairing mechanism in CeCoIn5 revisited

2020 ◽  
Vol 102 (20) ◽  
Author(s):  
T. J. Reber ◽  
J. D. Rameau ◽  
C. Petrovic ◽  
Hasnain Hafiz ◽  
M. Lindroos ◽  
...  
Keyword(s):  
Pairing Mechanism ◽  
Superconducting Pairing
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