Dimensionality of a strongly interacting 2D-3D Fermi-Fermi mixture from the perspective of superfluid instability and excitation properties
Abstract
We theoretically investigate strong-coupling properties of an attractively interacting Fermi atomic gas, where the Cooper-pair formation occurs between atoms belonging to different dimensional bands. Including pairing fluctuations within the framework of the self-consistent T-matrix approximation (SCTMA), we examine how the BCS-type superfluid phase transition temperature Tc varies as one moves from the 3D-3D to the 2D-3D system, in the wide parameter region with respect to the strength of the pairing interaction. In the 2D-3D limit, we find that, while the mean-field BCS theory predicts Tc>0 in the strong-coupling regime, Tc is remarkably suppressed down to zero by pairing fluctuations that are strongly enhanced by the mixed-dimensionality of the system. As the origin of this, we clarify that the lower-dimensional (2D) component dominates the superfluid instability, so that the vanishing Tc is the same phenomenon as that in the 2D-2D case. We also point out that this can already be seen in the mean-field level, when one examines the propagation of the Goldstone mode. On the other hand, we find that the pseudogap phenomenon, which is known as a precursor of Cooper-pair formation, exhibits a 3D character of the 2D-3D system. These results indicate that the dimensionality of a strongly interacting Fermi gas depends on what we observe.
Versions
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BibTeX
@misc{takeda2026dimensionality,
title = {{Dimensionality of a strongly interacting 2D-3D Fermi-Fermi mixture from the perspective of superfluid instability and excitation properties}},
author = {Haruka Takeda and Saki Hirai and Shumpei Iwasaki and Yoji Ohashi},
howpublished = {arXiv},
year = {2026},
month = may,
doi = {10.48550/arxiv.2605.30986},
eprint = {2605.30986},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.30986},
}
RIS
TY - UNPB
TI - Dimensionality of a strongly interacting 2D-3D Fermi-Fermi mixture from the perspective of superfluid instability and excitation properties
AU - Haruka Takeda
AU - Saki Hirai
AU - Shumpei Iwasaki
AU - Yoji Ohashi
PY - 2026
DA - 2026/05/29
PB - arXiv
DO - 10.48550/arxiv.2605.30986
UR - https://arxiv.org/abs/2605.30986
AB - We theoretically investigate strong-coupling properties of an attractively interacting Fermi atomic gas, where the Cooper-pair formation occurs between atoms belonging to different dimensional bands. Including pairing fluctuations within the framework of the self-consistent T-matrix approximation (SCTMA), we examine how the BCS-type superfluid phase transition temperature T_c varies as one moves from the 3D-3D to the 2D-3D system, in the wide parameter region with respect to the strength of the pairing interaction. In the 2D-3D limit, we find that, while the mean-field BCS theory predicts T_c>0 in the strong-coupling regime, T_c is remarkably suppressed down to zero by pairing fluctuations that are strongly enhanced by the mixed-dimensionality of the system. As the origin of this, we clarify that the lower-dimensional (2D) component dominates the superfluid instability, so that the vanishing T_c is the same phenomenon as that in the 2D-2D case. We also point out that this can already be seen in the mean-field level, when one examines the propagation of the Goldstone mode. On the other hand, we find that the pseudogap phenomenon, which is known as a precursor of Cooper-pair formation, exhibits a 3D character of the 2D-3D system. These results indicate that the dimensionality of a strongly interacting Fermi gas depends on what we observe.
ER -