High-resolution resonant inelastic x-ray scattering study of the electron-phonon coupling in honeycomb alpha-Li2IrO3
PHYSICAL REVIEW B 100:22 (2019) ARTN 224303
Abstract:
© 2019 American Physical Society. The excitations in honeycomb α-Li2IrO3 have been investigated with high-resolution resonant inelastic X-ray scattering (RIXS) at the O K edge. The low-energy response is dominated by a fully resolved ladder of excitations, which we interpret as being due to multiphonon processes in the presence of strong electron-phonon coupling (EPC). At higher energies, the orbital excitations are shown to be dressed by phonons. The high quality of the data permits a quantitative test of the analytical model for the RIXS cross section, which has been proposed to describe EPC in transition-metal oxides (TMOs). We find that the magnitude of the EPC is comparable to that found for a range of 3d TMOs. This indicates that EPC may be of equal importance in determining the phenomenology displayed by corresponding 5d-based systems.Chemical tuning between triangular and honeycomb structures in a 5d spin-orbit Mott insulator
University of Oxford (2019)
Abstract:
the deposited package contains resistivity and x-ray diffraction data on the layered potassium-iridate materials KxIryO2 We report structural studies of the spin-orbit Mott insulator family KxIryO2, with triangular layers of edge-sharing IrO6 octahedra bonded by potassium ions. The potassium content acts as a chemical tuning parameter to control the amount of charge in the Ir-O layers. Unlike the isostructural families with Ir replaced by Co or Rh (y=1), which are metallic over a range of potassium compositions x, we instead find insulating behaviour with charge neutrality achieved via iridium vacancies, which order in a honeycomb supercell above a critical composition. By performing density functional theory calculations we attribute the observed behaviour to a subtle interplay of crystal-field environment, local electronic correlations and strong spin-orbit interaction at the Ir4+ sites, making this structural family a candidate to display Kitaev magnetism in the experimentally unexplored regime that interpolates between triangular and honeycomb structures.Spin dynamics and field-induced magnetic phase transition in the honeycomb Kitaev magnet alpha-Li2IrO3
University of Oxford (2019)
Abstract:
The deposited package contains magnetic susceptibility, muon spin relaxation, powder inelastic neutron scattering and pulsed-field magnetization data of the honeycomb Kitaev magnet alpha-Li2IrO3. The readme file inside the .zip archive contains detailed information about the individual file formats in the data archive.Spin dynamics of coupled spin ladders near quantum criticality in Ba2CuTeO6
Physical review B: Condensed matter and materials physics American Physical Society (2018)
Abstract:
We report inelastic neutron scattering measurements of the magnetic excitations in Ba2CuTeO6, proposed by ab initio calculations to magnetically realize weakly coupled antiferromagnetic two-leg spin-1/2 ladders. Isolated ladders are expected to have a singlet ground state protected by a spin gap. Ba2CuTeO6 orders magnetically, but with a small Neel temperature relative to the exchange strength, suggesting that the interladder couplings are relatively small and only just able to stabilize magnetic order, placing Ba2CuTeO6 close in parameter space to the critical point separating the gapped phase and Neel order. Through comparison of the observed spin dynamics with linear spin wave theory and quantum Monte Carlo calculations, we propose values for all relevant intra- and interladder exchange parameters, which place the system on the ordered side of the phase diagram in proximity to the critical point. We provide further cross-checks of the extracted parameters by comparison with high field magnetization data.Probing α − RuCl3 beyond magnetic order: effects of temperature and magnetic field
Physical Review Letters American Physical Society 120:7 (2018) 077203