Doping-driven structural distortion in the bilayer iridate (Sr1−xLax)3Ir2O

Abstract

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 P 21/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.

Pressure-induced formation of rhodium zigzag chains in the honeycomb rhodateLi2RhO3

“…The electronic states of Li 2 RhO 3 are affected by the distortion of the RhO 6 octahedra. Therefore, we followed the pressure dependence of the octahedral distortion using the bond-length distortion ∆ oct and the bond-angle distortion σ 2 oct [38][39][40]. The bond-length distortion is defined as ∆ oct = 1 (6) comparable to the results in Ref.…”

Polarized Raman spectroscopy study of metallic (Sr1−xLax)3Jin1, Li2, Liu3 et al. 2019Phys. Rev. BSelf Cite5071View full textAdd to dashboardCite

“…Raman measurements were performed in the backscattering geometry, using the 514 nm line of an argon-ion laser and a Dilor XY triple monochromator spectrometer. The incident optical fluence was maintained at 1.2 mW over a beam diameter of 20 µm that is smaller than the size of reported monoclinic structural domains [30]. To perform the RA polarized Raman measurements ( Fig.…”

“…By surveying all of the Raman tensors of the D 4h subgroups that have finite tensor elements in the aa, ab, and a a channels but is fully suppressed in the a b one (see Supplementary Section 1 [32]), we found that this mode belongs to the A (A g , A 1 , and A) symmetry of the orthorhombic subgroups (D 2h , C 2v , and D 2 , respectively). Considering the fact that this mode is only present at low temperatures (see Supplementary Section 2 [32]) while second harmonic generation shows no changes from room to low temperature [30], we ruled out the two noncentrosymmetric candidates (C 2v and D 2 ) and uniquely identified the point group D 2h for the emergent order.…”

Electron doping in Sr3Ir2O7 : Collapse of band gap and magnetic order

“…Another open question concerns the shifts in lattice parameters upon lanthanum doping. 14,24 We present new experimental data on these shifts. In our calculations, we separate the effects of ionic substitution from electron doping.…”