Hyperhoneycomb Iridate $\beta \text{-}{\mathrm{Li}}_2{\mathrm{IrO}}_3$ as a Platform for Kitaev Magnetism

Journal Article · Sun Feb 01 00:00:00 EST 2015 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.114.077202· OSTI ID:1392960

Takayama, T.; Kato, A.; Dinnebier, R.; Nuss, J.; Kono, H.; Veiga, L. S. I.; Fabbris, G.; Haskel, D.; Takagi, H.

A complex iridium oxide β-Li₂IrO₃ crystallizes in a hyperhoneycomb structure, a three-dimensional analogue of honeycomb lattice, and is found to be a spin-orbital Mott insulator with J_eff = 1/2 moment. Ir ions are connected to the three neighboring Ir ions via Ir-O₂-Ir bonding planes, which very likely gives rise to bond-dependent ferromagnetic interactions between the J_eff = 1/2 moments, an essential ingredient of Kitaev model with a spin liquid ground state. Dominant ferromagnetic interaction between J(eff) = 1/2 moments is indeed confirmed by the temperature dependence of magnetic susceptibility chi(T) which shows a positive Curie-Weiss temperature $$\theta$$(CW) similar to +40 K. A magnetic ordering with a very small entropy change, likely associated with a noncollinear arrangement of J_eff = 1/2 moments, is observed at T_c = 38 K. With the application of magnetic field to the ordered state, a large moment of more than 0.35 μ_B/Ir is induced above 3 T, a substantially polarized J_eff = 1/2 state. We argue that the close proximity to ferromagnetism and the presence of large fluctuations evidence that the ground state of hyperhoneycomb β-Li₂IrO₃ is located in close proximity of a Kitaev spin liquid.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1392960
• Journal Information: Physical Review Letters, Vol. 114, Issue 7; ISSN 0031-9007
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English