Hyperhoneycomb Iridate as a Platform for Kitaev Magnetism
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 Jeff = 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 Jeff = 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 Jeff = 1/2 moments, is observed at Tc = 38 K. With the application of magnetic field to the ordered state, a large moment of more than 0.35 μB/Ir is induced above 3 T, a substantially polarized Jeff = 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
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