@article{oai:repo.qst.go.jp:00074807,
 author = {Takayama, T. and Krajewska, A. and S. Gibbs, A. and N. Yaresko, A. and Ishii, H. and Yamaoka, H. and Ishii, K. and Hiraoka, N. and P. Funnell, N. and L. Bull, C. and Takagi, H. and Ishii, Kenji},
 issue = {12},
 journal = {Physical Review B},
 month = {Mar},
 note = {Hyperhoneycomb iridate β-Li2IrO3 is a three-dimensional analog of two-dimensional honeycomb iridates, such as α-Li2IrO3, which recently appeared as another playground for the physics of Kitaev-type spin liquid. β-Li2IrO3 shows a noncollinear spiral ordering of spin-orbital-entangled Jeff = 1/2 moments at low temperatures below 38 K, which is known to be suppressed under a pressure of ∼2 GPa. In addition, a structural transition is observed at PS ∼ 4 GPa at room temperature. Using the neutron powder diffraction technique, the crystal structure in the high-pressure phase of β-Li2IrO3 above PS was refined, which indicates the formation of Ir2 dimers on the zigzag chains, with an Ir-Ir distance of ∼2.66 Å, even shorter than that of metallic Ir. We argue that the strong dimerization stabilizes the bonding molecular-orbital state comprising the two local dzx orbitals in the Ir-O2-Ir bond plane, which conflicts with the equal superposition of dxy, dyz, and dzx orbitals in the Jeff = 1/2 wave function produced by strong spin-orbit coupling. The results of resonant inelastic x-ray scattering measurements and the electronic structure calculations are fully consistent with the collapse of the Jeff = 1/2 state. The competition between the spin-orbital-entangled Jeff = 1/2 state and molecular-orbital formation is most likely universal in honeycomb-based Kitaev materials.},
 pages = {125127-1--125127-7},
 title = {Pressure-induced collapse of the spin-orbital Mott state in the hyperhoneycomb iridate β-Li2IrO3},
 volume = {99},
 year = {2019}
}