scholarly journals Pressure dependence of critical temperature in MgB2 and two-bands Eliashberg theory

2005 ◽  
Vol 423 (3-4) ◽  
pp. 96-102 ◽  
Author(s):  
G.A. Ummarino
Keyword(s):  
Critical Temperature ◽  
Pressure Dependence ◽  
Eliashberg Theory

The gap over critical temperature ratio in Eliashberg theory

1995 ◽  
Vol 93 (2) ◽  
pp. 113-117 ◽  
Author(s):  
R. Combescot ◽  
G. Varelogiannis
Keyword(s):  
Critical Temperature ◽  
Temperature Ratio ◽  
Eliashberg Theory

scholarly journals Pressure dependence of the superconducting critical temperature ofTl2Ba2Ca2Cu3O10+yandTl2Ba2Ca3Cu4O12+yup to 21 GPa

1996 ◽  
Vol 54 (14) ◽  
pp. 10175-10185 ◽  
Author(s):  
D. Tristan Jover ◽  
R. J. Wijngaarden ◽  
R. Griessen ◽  
E. M. Haines ◽  
J. L. Tallon ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Pressure Dependence

Studies of Temperature and Pressure Dependence in Thermocompression Gold Joints

2005 ◽  
Author(s):  
X. F. Ang ◽  
G. G. Zhang ◽  
J. Wei ◽  
Z. Chen ◽  
C. C. Wong
Keyword(s):  
Shear Strength ◽  
Critical Temperature ◽  
Pressure Dependence ◽  
Bonding Temperature ◽  
Interfacial Stress ◽  
3D Integration ◽  
Bonding Pressure ◽  
Barrier Films ◽  
Linear Rise ◽  
Temperature And Pressure

Low temperature interconnection is a critical component of 3D integration and packaging technology. In this study, we investigate the characteristics of thermocompression metal bonding using gold stud bumps formed on Si die in the temperature range of 100-300 °C and the pressure range of 200–600 g/bump. We observed a critical bonding temperature below which bonding did not occur and above which shear strength improves linearly with bonding temperature. This critical temperature can be interpreted to be the onset of the break-up of organic barrier films while the linear rise in shear strength can be attributed to the increase in the true bonded area. Above this critical temperature, the tensile strength of the Au-Au bond exhibits a maximum with increasing bonding pressure. This can be related to the pressure dependence of the interfacial stress distribution and its effect on unbonded radius, r. SEM fractographs of the failed surfaces suggest a combination of cohesive and adhesive failures along the bonded interface.

scholarly journals Lifshitz transitions and zero point lattice fluctuations in sulfur hydride showing near room temperature superconductivity

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Antonio Bianconi ◽  
Thomas Jarlborg
Keyword(s):  
Critical Temperature ◽  
Fermi Surface ◽  
Fermi Energy ◽  
Room Temperature ◽  
Zero Point ◽  
Shape Resonance ◽  
Eliashberg Theory ◽  
Lifshitz Transitions ◽  
Point Lattice ◽  
Lattice Fluctuations

AbstractEmerets’s experiments on pressurized sulfur hydride have shown that H3S metal has the highest known superconducting critical temperature Tc = 203 K. The Emerets data show pressure induced changes of the isotope coefficient between 0.25 and 0.5, in disagreement with Eliashberg theory which predicts a nearly constant isotope coefficient.We assign the pressure dependent isotope coefficient to Lifshitz transitions induced by pressure and zero point lattice fluctuations. It is known that pressure could induce changes of the topology of the Fermi surface, called Lifshitz transitions, but were neglected in previous papers on the H3S superconductivity issue. Here we propose thatH3S is a multi-gap superconductor with a first condensate in the BCS regime (located in the large Fermi surface with high Fermi energy) which coexists with second condensates in the BCS-BEC crossover regime (located on the Fermi surface spots with small Fermi energy) near the and Mpoints.We discuss the Bianconi-Perali-Valletta (BPV) superconductivity theory to understand superconductivity in H3S since the BPV theory includes the corrections of the chemical potential due to pairing and the configuration interaction between different condensates, neglected by the Eliashberg theory. These two terms in the BPV theory give the shape resonance in superconducting gaps, similar to Feshbach resonance in ultracold fermionic gases, which is known to amplify the critical temperature. Therefore this work provides some key tools useful in the search for new room temperature superconductors.

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