Low Temperature Physics: 32, 406 (2006); https://doi.org/10.1063/1.2199443 (18 pages)
Физика Низких Температур: Том 32, Выпуск 4-5 (Апрель 2006), c. 538-560 ( к оглавлению , назад )
Applying BCS-BEC crossover theory to high-temperature superconductors and ultracold atomic Fermi gases
Qijin Chen1, Jelena Stajic2, and K. Levin1
1James Franck Institute and Department of Physics, University of Chicago Chicago, Illinois, 60637 USA
2Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 USA
Received September 13, 2005
This review is written at the time of the twentieth anniversary of the discovery of high-temperature
superconductors, which, nearly coincides with the important discovery of the superfluid phases of ultracold trapped fermionic atoms. We show how these two subjects have much in common. Both have been addressed from the perspective of the BCS–Bose–Einstein condensation (BEC) crossover scenario, which is designed to treat short coherence length superfluids with transition temperatures which are «high», with respect to the Fermi energy. A generalized mean field treatment of BCS–BEC crossover at general temperatures T, based on the BCS–Leggett ground
state, has met with remarkable success in the fermionic atomic systems. Here we summarize this
success in the context of four different cold atom experiments, all of which provide indications, direct
or indirect, for the existence of a pseudogap. This scenario also provides a physical picture of the pseudogap phase in the underdoped cuprates which is a central focus of high Tc research. We summarize successful applications of BCS–BEC crossover to key experiments in high Tc systems including the phase diagram, specific heat, and vortex core STM data, along with the Nernst effect, and exciting recent data on the superfluid density in very underdoped samples.
Ключевые слова: high-temperature Tc superconductivity, Bose–Einstein condensation, fermionic atomic systems.