%0 Journal Article %J PHYSICAL REVIEW B %D 2016 %T Bounds on nanoscale nematicity in single-layer FeSe/SrTiO3 %A Huang, Dennis %A Webb, Tatiana A. %A Fang, Shiang %A Song, Can-Li %A Chang, Cui-Zu %A Moodera, Jagadeesh S. %A Efthimios Kaxiras %A Hoffman, Jennifer E. %X We use scanning tunneling microscopy (STM) and quasiparticle interference (QPI) imaging to investigate the low-energy orbital texture of single-layer FeSe/SrTiO3. We develop a T-matrix model of multiorbital QPI to disentangle scattering intensities from Fe 3d(xz) and 3d(yz) bands, enabling the use of STM as a nanoscale detection tool of nematicity. By sampling multiple spatial regions of a single-layer FeSe/SrTiO3 film, we quantitatively exclude static xz/yz orbital ordering with domain size larger than delta r(2) = 20 nm x 20 nm, xz/yz Fermi wave vector difference larger than delta k = 0.014 pi, and energy splitting larger than delta E = 3.5 meV. The lack of detectable ordering pinned around defects places qualitative constraints on models of fluctuating nematicity. %B PHYSICAL REVIEW B %V 93 %8 MAR 18 %G eng %N 12 %R 10.1103/PhysRevB.93.125129