Quasiparticle interference in the unconventional metamagnetic compound Sr₃Ru₂O₇

Quasiparticle interference (QPI) in spectroscopic imaging scanning tunneling microscopy provides a powerful method to detect orbital band structures and orbital ordering patterns in transition-metal oxides. We use the T -matrix formalism to calculate the QPI spectra for the unconventional metamagnetic system of Sr₃ Ru₂ O₇ with a t _2g -orbital band structure. A detailed tight-binding model is constructed accounting for features such as spin-orbit coupling, bilayer splitting, and the staggered rotation of the RuO octahedra. The band parameters are chosen by fitting the calculated Fermi surfaces with those measured in the angular-resolved photoemission spectroscopy experiment. The calculated quasiparticle interference at zero magnetic field exhibits a hollow squarelike feature arising from the nesting of the quasi-one-dimensional d_xz and d_yz orbital bands, in agreement with recent measurements by Lee [Nat. Phys. 5, 800 (2009)]. Rotational symmetry breaking in the nematic metamagnetic state also manifests in the quasiparticle interference spectra.