Magnetic excitations and interactions in the Kitaev hyperhoneycomb iridate β−Li2IrO3

Materials with Kitaev interactions are increasingly studied for their potential to realize spin-liquid physics and Majorana quasiparticle excitations, but Kitaev materials with precisely refined spin exchange remain few. Here, the authors present a comprehensive experimental study, using powder inelastic neutron scattering, terahertz spectroscopy, and heat capacity measurements, that refines the spin exchange Hamiltonian of $\ensuremath{\beta}$-Li${}_{2}$IrO${}_{3}$. The results provide strong evidence for a dominant ferromagnetic Kitaev interaction and place $\ensuremath{\beta}$-Li${}_{2}$IrO${}_{3}$ in close proximity to the Kitaev spin-liquid phase.