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

作　　者：Shu-Yang Wang Jing-Wei Jiang Yue-Ran Shi Qiongyi He Qihuang Gong Wei Zhang 

机构地区：[1]State Key Laboratory of Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China [2]Department of Physics, Renmin University of China, Beifing 100872, China [3]Collaborative Innovation Center of Quantum Matter, Beijing 100871, China [4]Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030005, China [5]Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing 100872, China

出　　处：《Frontiers of physics》2017年第5期27-33,共7页物理学前沿（英文版）

基　　金：Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant Nos. 11274009, 11274025, 11434011, and 61675007）, the National 11522436, 11622428, 61475006, Key R＆D Program （Grant Nos. 2013CB922000 and 2016YFA0301201）, the Ministry of Science and Technology of China （Grant No. 2016YFA0301302）, and the Research Funds of Renmin University of China （Grant Nos. 10XNL016 and 16XNLQ03）.

摘　　要：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 px-orbital bands, respectively. We show that owing to the relative inversion of the band structures of the s and px 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 π along 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 TBKT for different phases.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 px-orbital bands, respectively. We show that owing to the relative inversion of the band structures of the s and px 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 π along 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 TBKT for different phases.

关 键 词：ultracold Fermi gas SUPERFLUID optical lattice 

分 类 号：O413.3[理学—理论物理] U213.2[理学—物理]