Chemical tuning between triangular and honeycomb structures in a 5d spin-orbit Mott insulator
Physical Review B American Physical Society 100 (2019) 214113
Abstract:
We report structural studies of the spin-orbit Mott insulator family K x Ir y O 2 , with triangular layers of edge-sharing IrO 6 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 behavior with charge neutrality achieved via iridium vacancies, which order in a honeycomb supercell above a critical composition x c . By performing density functional theory calculations we attribute the observed behavior to a subtle interplay of crystal-field environment, local electronic correlations, and strong spin-orbit interaction at the Ir 4 + sites, making this structural family a candidate to display Kitaev magnetism in the experimentally unexplored regime that interpolates between triangular and honeycomb structures.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.Weyl-like points from band inversions of spin-polarised surface states in NbGeSb
Nature Communications Springer Science and Business Media LLC 10:1 (2019) 5485
Modular thermal Hall effect measurement setup for fast-turnaround screening of materials over wide temperature range using capacitive thermometry
Review of Scientific Instruments AIP Publishing 90:10 (2019) 103904-103904
A series of magnon crystals appearing under ultrahigh magnetic fields in a kagomé antiferromagnet
ArXiv 1903.07283 (2019)