2013/12/04 by H. Tajima, Hiroyuki Tajima, Takashi Kashimura +7 · 36 citations
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Cuprate #Fermi gas #Pairing #Physics #Physics of Superconductivity and Magnetism #Pseudogap #Quantum many-body systems #Quantum mechanics #Spin (aerodynamics) #Superconductivity #Superfluidity #Thermodynamics #cond-mat.quant-gas
paper · pdf · doi:10.1103/physreva.89.033617
published in Physical Review A 89(3) (American Physical Society) · 19 pages, 9 figures
arxiv created 2013/12/04 · openalex publication_date 2014/03/12 · arxiv updated 2015/10/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate the uniform spin susceptibility \ensuremathχs in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover regime of an ultracold Fermi gas. Including pairing fluctuations within the framework of an extended T-matrix approximation, we show that \ensuremathχs exhibits nonmonotonic temperature dependence in the normal state. In particular, \ensuremathχs is suppressed near the superfluid phase transition temperature Tc due to strong pairing fluctuations. To characterize this anomalous behavior, we introduce the spin-gap temperature Ts as the temperature at which \ensuremathχs takes a maximum value. Determining Ts in the whole BCS-BEC crossover region, we identify the spin-gap regime in the phase diagram of a Fermi gas in terms of the temperature and the strength of a pairing interaction. We also clarify how the spin-gap phenomenon is related to the pseudogap phenomenon appearing in the single-particle density of states. Our results indicate that an ultracold Fermi gas in the BCS-BEC crossover region is a very useful system to examine the pseudogap phenomenon and the spin-gap phenomenon in a unified manner.