TY - JOUR
T1 - Spin susceptibility and effects of a harmonic trap in the BCS-BEC crossover regime of an ultracold Fermi gas
AU - Tajima, Hiroyuki
AU - Hanai, Ryo
AU - Ohashi, Yoji
N1 - Funding Information:
We thank T. Kashimura, R. Watanabe, D. Inotani, and M. Ota for useful discussions. This work was supported by KiPAS project at Keio University. H.T. and R.H. were supported by a Grant-in-Aid for JSPS fellows (Grants No. 17J03975 and No. 17J01238). Y.O. was also supported by Grant-in-Aid for Scientific research from MEXT and JSPS in Japan (Grants No. 16K05503, No. 15K00178, and No. 15H00840).
Publisher Copyright:
© 2017 American Physical Society.
PY - 2017/9/11
Y1 - 2017/9/11
N2 - We theoretically investigate magnetic properties of a trapped ultracold Fermi gas. Including pairing fluctuations within the framework of an extended T-matrix approximation, as well as effects of a harmonic trap in the local density approximation, we calculate the local spin susceptibility χt(r,T) in the Bardeen-Cooper-Schrieffer-Bose-Einstein condensation crossover region. We show that pairing fluctuations cause nonmonotonic temperature dependence of χt(r,T). Although this behavior looks similar to the spin-gap phenomenon associated with pairing fluctuations in a uniform Fermi gas, the trapped case is found to also be influenced by the temperature-dependent density profile, in addition to pairing fluctuations. We demonstrate how to remove this extrinsic effect from χt(r,T), to study the interesting spin-gap phenomenon purely originating from pairing fluctuations. Since experiments in cold-atom physics are always done in a trap, our results would be useful for the assessment of preformed pair scenario, from the viewpoint of spin-gap phenomenon.
AB - We theoretically investigate magnetic properties of a trapped ultracold Fermi gas. Including pairing fluctuations within the framework of an extended T-matrix approximation, as well as effects of a harmonic trap in the local density approximation, we calculate the local spin susceptibility χt(r,T) in the Bardeen-Cooper-Schrieffer-Bose-Einstein condensation crossover region. We show that pairing fluctuations cause nonmonotonic temperature dependence of χt(r,T). Although this behavior looks similar to the spin-gap phenomenon associated with pairing fluctuations in a uniform Fermi gas, the trapped case is found to also be influenced by the temperature-dependent density profile, in addition to pairing fluctuations. We demonstrate how to remove this extrinsic effect from χt(r,T), to study the interesting spin-gap phenomenon purely originating from pairing fluctuations. Since experiments in cold-atom physics are always done in a trap, our results would be useful for the assessment of preformed pair scenario, from the viewpoint of spin-gap phenomenon.
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U2 - 10.1103/PhysRevA.96.033614
DO - 10.1103/PhysRevA.96.033614
M3 - Article
AN - SCOPUS:85029575263
SN - 2469-9926
VL - 96
JO - Physical Review A
JF - Physical Review A
IS - 3
M1 - 033614
ER -