Chemical tuning between triangular and honeycomb structures in a 5d spin-orbit Mott insulator

Journal article

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.

Authors: Johnson, R; Broeders, I; Mehlawat, K; Li, Y; Singh, Y

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review B
• Volume: 100
• Article number: 214113
• Publication date: 2019-12-18
• Acceptance date: 2019-10-31
• DOI: 10.1103/PhysRevB.100.214113
• EISSN: 2469-9969
• ISSN: 2469-9950
• Keywords: FFR