Neutron single crystal diffraction and rotational anisotropy optical second harmonic generation data are presented resolving the nature of the structural distortion realized in electron-doped (Sr1−xLax)3Ir2O7 with x=0.035 and x=0.071. Once electrons are introduced into the bilayer spin-orbit assisted Mott insulator Sr3Ir2O7, previous studies have identified the appearance of a low temperature structural distortion and have suggested the presence of a competing electronic instability in the phase diagram of this material. Our measurements resolve a lowering of the structural symmetry from monoclinic C2/c to monoclinic P21/c and the creation of two unique Ir sites within the chemical unit cell as the lattice distorts below a critical temperature TS. Details regarding the modifications to oxygen octahedral rotations and tilting through the transition are discussed as well as the evolution of the low temperature distorted lattice as a function of carrier substitution.
@article{arxiv.1705.04720,
title = {Doping driven structural distortion in the bilayer iridate (Sr$_{1-x}$La$_x$)$_3$Ir$_2$O$_7$},
author = {Tom Hogan and Xiaoping Wang and H. Chu and David Hsieh and Stephen D. Wilson},
journal= {arXiv preprint arXiv:1705.04720},
year = {2017}
}