Fulde–Ferrell–Larkin–Ovchinnikov pairing states between <i>s</i>- and <i>p</i>-orbital fermions

doi:10.1007/s11467-017-0681-y

Front. Phys.

2017, Vol. 12

Issue (5) : 126701 https://doi.org/10.1007/s11467-017-0681-y

RESEARCH ARTICLE

Fulde–Ferrell–Larkin–Ovchinnikov pairing states between s- and p-orbital fermions

Shu-Yang Wang¹, Jing-Wei Jiang¹, Yue-Ran Shi², Qiongyi He^1,^3,⁴, Qihuang Gong^1,^3,⁴, Wei Zhang^2,⁵(

)

¹. State Key Laboratory of Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
². Department of Physics, Renmin University of China, Beijing 100872, China
³. Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
⁴. Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
⁵. Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing 100872, China

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Abstract

We study the pairing states in a largely imbalanced two-component Fermi gas loaded in an anisotropic two-dimensional optical lattice, where the spin-up and spin-down fermions are filled to the s- and p_x-orbital bands, respectively. We show that owing to the relative inversion of the band structures of the s and p_x orbitals, the system favors pairing between two fermions on the same side of the Brillouin zone, leading to a large stable regime for states with a finite center-of-mass momentum, i.e., the Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state. In particular, when two Fermi surfaces are close in momentum space, a nesting effect stabilizes a special type of π-FFLO phase with a spatial modulation of πalong the easily tunneled x direction. We map out the zero-temperature phase diagrams within the mean-field approach for various aspect ratios within the two-dimensional plane and calculate the Berezinskii–Kosterlitz–Thouless (BKT) transition temperatures T_BKT for different phases.

Keywords ultracold Fermi gas superfluid optical lattice

Corresponding Author(s): Wei Zhang

Issue Date: 22 May 2017

Cite this article:

Shu-Yang Wang,Jing-Wei Jiang,Yue-Ran Shi, et al. Fulde–Ferrell–Larkin–Ovchinnikov pairing states between s- and p-orbital fermions[J]. Front. Phys. , 2017, 12(5): 126701.

URL:

https://academic.hep.com.cn/fop/EN/10.1007/s11467-017-0681-y
https://academic.hep.com.cn/fop/EN/Y2017/V12/I5/126701

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