Abstract
We use resonant elastic and inelastic x-ray scattering at the Ir- edge to study the doping-dependent magnetic order, magnetic excitations, and spin-orbit excitons in the electron-doped bilayer iridate (). With increasing doping , the three-dimensional long range antiferromagnetic order is gradually suppressed and evolves into a three-dimensional short range order across the insulator-to-metal transition from to 0.05, followed by a transition to two-dimensional short range order between and 0.065. Because of the interactions between the pseudospins and the emergent itinerant electrons, magnetic excitations undergo damping, anisotropic softening, and gap collapse, accompanied by weakly doping-dependent spin-orbit excitons. Therefore, we conclude that electron doping suppresses the magnetic anisotropy and interlayer couplings and drives into a correlated metallic state with two-dimensional short range antiferromagnetic order. Strong antiferromagnetic fluctuations of the moments persist deep in this correlated metallic state, with the magnon gap strongly suppressed.
- Received 28 August 2016
DOI:https://doi.org/10.1103/PhysRevLett.118.027202
© 2017 American Physical Society