Microscopic route to nematicity in Sr3Ru2O7

An anisotropic metallic phase dubbed electronic nematic phase bounded by two consecutive metamagnetic transitions has been reported in the bilayer ruthenate Sr3Ru2O7. 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 t2g orbitals, spin-orbit coupling and the rotation of RuO6 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 (±, 0) and (0,±), then strongly competes with ferromagnetic order but pre-empts it via a finite nearest neighbor interaction. We discuss experimental means to confirm our proposal.

Christoph M. Puetter,1  Jeffrey G. Rau,1  and Hae-Young Kee1, 2,
1Department of Physics, University of Toronto, Toronto, Ontario, Canada M5S 1A7
2School of Physics, Korea Institute for Advanced Study, Seoul 130-722, Republic of Korea