scholarly journals Bose-Einstein Condensation ofS=1Nickel Spin Degrees of Freedom inNiCl2−4SC(NH2)2

2006 ◽  
Vol 96 (7) ◽  
Author(s):  
V. S. Zapf ◽  
D. Zocco ◽  
B. R. Hansen ◽  
M. Jaime ◽  
N. Harrison ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Bose Einstein

scholarly journals Bose-Einstein condensation superconductivity induced by disappearance of the nematic state

2020 ◽  
Vol 6 (45) ◽  
pp. eabb9052
Author(s):  
Takahiro Hashimoto ◽  
Yuichi Ota ◽  
Akihiro Tsuzuki ◽  
Tsubaki Nagashima ◽  
Akiko Fukushima ◽  
...  
Keyword(s):  
Ultracold Atoms ◽  
Degrees Of Freedom ◽  
Photoemission Spectroscopy ◽  
Einstein Condensation ◽  
Energy Bands ◽  
Iron Based Superconductors ◽  
Bose Einstein Condensation ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Nematic State ◽  
Bose Einstein

The crossover from the superconductivity of the Bardeen-Cooper-Schrieffer (BCS) regime to the Bose-Einstein condensation (BEC) regime holds a key to understanding the nature of pairing and condensation of fermions. It has been mainly studied in ultracold atoms, but in solid systems, fundamentally previously unknown insights may be obtained because multiple energy bands and coexisting electronic orders strongly affect spin and orbital degrees of freedom. Here, we provide evidence for the BCS-BEC crossover in iron-based superconductors FeSe1 − xSx from laser-excited angle-resolved photoemission spectroscopy. The system enters the BEC regime with x = 0.21, where the nematic state that breaks the orbital degeneracy is fully suppressed. The substitution dependence is opposite to the expectation for single-band superconductors, which calls for a new mechanism of BCS-BEC crossover in this system.

Systems with Condensates and Pairing

2018 ◽  
Author(s):  
Klaus Morawetz
Keyword(s):  
Critical Parameters ◽  
Einstein Condensation ◽  
Cooper Pairs ◽  
Pair Breaking ◽  
Systematic Theory ◽  
Bose Einstein Condensation ◽  
T Matrix ◽  
The Stability ◽  
Bose Einstein

The Bose–Einstein condensation and appearance of superfluidity and superconductivity are introduced from basic phenomena. A systematic theory based on the asymmetric expansion of chapter 11 is shown to correct the T-matrix from unphysical multiple-scattering events. The resulting generalised Soven scheme provides the Beliaev equations for Boson’s and the Nambu–Gorkov equations for fermions without the usage of anomalous and non-conserving propagators. This systematic theory allows calculating the fluctuations above and below the critical parameters. Gap equations and Bogoliubov–DeGennes equations are derived from this theory. Interacting Bose systems with finite temperatures are discussed with successively better approximations ranging from Bogoliubov and Popov up to corrected T-matrices. For superconductivity, the asymmetric theory leading to the corrected T-matrix allows for establishing the stability of the condensate and decides correctly about the pair-breaking mechanisms in contrast to conventional approaches. The relation between the correlated density from nonlocal kinetic theory and the density of Cooper pairs is shown.

scholarly journals Bose Einstein condensation in a magnetic double-well potential

2003 ◽  
Vol 5 (2) ◽  
pp. S119-S123 ◽  
Author(s):  
T G Tiecke ◽  
M Kemmann ◽  
Ch Buggle ◽  
I Shvarchuck ◽  
W von Klitzing ◽  
...  
Keyword(s):  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Bose Einstein ◽  
Double Well Potential

Bose-Einstein condensation of large numbers of atoms in a magnetic time-averaged orbiting potential trap

1998 ◽  
Vol 57 (6) ◽  
pp. R4114-R4117 ◽  
Author(s):  
D. J. Han ◽  
R. H. Wynar ◽  
Ph. Courteille ◽  
D. J. Heinzen
Keyword(s):  
Einstein Condensation ◽  
Bose Einstein Condensation ◽  
Large Numbers ◽  
Potential Trap ◽  
Bose Einstein
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