Doh Hyeonjin, Song Matthew, Kee Hae-Young
Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada.
Phys Rev Lett. 2006 Dec 22;97(25):257001. doi: 10.1103/PhysRevLett.97.257001. Epub 2006 Dec 18.
The previously studied Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is stabilized by a magnetic field via the Zeeman coupling in spin-singlet superconductors. Here we suggest a novel route to achieve nonzero center-of-mass momentum pairing states in superconductors with Fermi surface nesting. We investigate two-dimensional superconductors under a uniform external current, proportional to a finite pair momentum of q(e). We find that an FFLO state with a spontaneous pair momentum of q(s) is stabilized above a certain critical current that depends on the direction of the external current. A finite q(s) arises in order to make the total pair-momentum of q(t)(=q(s) + q(e)) perpendicular to the nesting vector, which is independent of spin states of Cooper pairs. We also discuss experimental signatures of the FFLO state.
先前研究的富尔德-费雷尔-拉金-奥夫钦尼科夫（FFLO）态通过自旋单重态超导体中的塞曼耦合由磁场稳定。在此，我们提出一种在具有费米面嵌套的超导体中实现非零质心动量配对态的新途径。我们研究了在均匀外电流下的二维超导体，该电流与有限的配对动量q(e)成正比。我们发现，具有自发配对动量q(s)的FFLO态在高于某个取决于外电流方向的临界电流时会被稳定下来。出现有限的q(s)是为了使总配对动量q(t)(=q(s) + q(e))垂直于嵌套矢量，这与库珀对的自旋态无关。我们还讨论了FFLO态的实验特征。
