Uniform spin susceptibility and spin-gap phenomenon in the BCS-BEC-crossover regime of an ultracold Fermi gas

Hiroyuki Tajima, Takashi Kashimura, Ryo Hanai, Ryota Watanabe, Yoji Ohashi

研究成果: Article

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We investigate the uniform spin susceptibility χs 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 χs exhibits nonmonotonic temperature dependence in the normal state. In particular, χs 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 χs 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.

元の言語English
記事番号033617
ジャーナルPhysical Review A - Atomic, Molecular, and Optical Physics
89
発行部数3
DOI
出版物ステータスPublished - 2014 3 12

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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