ChemInform Abstract: Bose-Einstein Condensation in Quantum Magnets

ChemInform ◽  
2015 ◽  
Vol 46 (9) ◽  
pp. no-no
Author(s):  
Vivien Zapf ◽  
Marcelo Jaime ◽  
C. D. Batista
2014 ◽  
Vol 86 (2) ◽  
pp. 563-614 ◽  
Author(s):  
Vivien Zapf ◽  
Marcelo Jaime ◽  
C. D. Batista

Author(s):  
Abdulla Rakhimov ◽  
Mukhtorali Nishonov ◽  
Luxmi Rani ◽  
Bilal Tanatar

Exploiting the analogy between ultracold atomic gases and the system of triplons, we study magneto-thermodynamic properties of dimerized quantum magnets in the framework of Bose–Einstein condensation (BEC). Particularly, introducing the inversion (or Joule–Thomson) temperature [Formula: see text] as the point where Joule–Thomson coefficient of an isenthalpic process changes its sign, we show that for a simple paramagnet, this temperature is infinite, while for three-dimensional (3D) dimerized quantum magnets it is finite and always larger than the critical temperature [Formula: see text] of BEC. Below the inversion temperature [Formula: see text], the system of triplons may be in a liquid phase, which undergoes a transition into a superfluid phase at [Formula: see text]. The dependence of the inversion temperature on the external magnetic field [Formula: see text] has been calculated for quantum magnets of TlCuCl3 and Sr3Cr2O8.


Author(s):  
Klaus Morawetz

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.


2003 ◽  
Vol 5 (2) ◽  
pp. S119-S123 ◽  
Author(s):  
T G Tiecke ◽  
M Kemmann ◽  
Ch Buggle ◽  
I Shvarchuck ◽  
W von Klitzing ◽  
...  

1998 ◽  
Vol 57 (6) ◽  
pp. R4114-R4117 ◽  
Author(s):  
D. J. Han ◽  
R. H. Wynar ◽  
Ph. Courteille ◽  
D. J. Heinzen

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