Microscopic route to nematicity inSr3Ru2O7

Abstract

An anisotropic metallic phase dubbed electronic nematic phase bounded by two consecutive metamagnetic transitions has been reported in the bilayer ruthenate ${\text{Sr}}_{3}{\text{Ru}}_{2}{\text{O}}_{7}$. It has also been shown that the nematic and the accompanying metamagnetic transitions are driven by an effective momentum-dependent quadrupole-type interaction. Here, we study the microscopic origin of such an effective interaction. To elucidate the mechanism behind the spontaneous Fermi-surface distortion associated with the nematic, we identify a simple tight-binding model based on ${t}_{2g}$ orbitals, spin-orbit coupling, and the rotation of ${\text{RuO}}_{6}$ octahedra as starting point, consistent with the Fermi surface obtained from recent angle-resolved photoemission data. Within an extended Hubbard model the nematic state, characterized by an anisotropy between the bands near $(\ifmmode\pm\else\textpm\fi{}\ensuremath{\pi},0)$ and $(0,\ifmmode\pm\else\textpm\fi{}\ensuremath{\pi})$, then strongly competes with ferromagnetic order but pre-empts it via a finite nearest-neighbor interaction. We discuss experimental means to confirm our proposal.