VI3 is a ferromagnet with planar honeycomb sheets of bonded V3+ ions held together by van der Waals forces. We apply neutron spectroscopy to measure the two-dimensional (J/Jc≈17) magnetic excitations in the ferromagnetic phase, finding two energetically gapped (Δ≈kBTc≈55K) and dispersive excitations. We apply a multilevel spin-wave formalism to describe the spectra in terms of two coexisting domains hosting differing V3+ orbital ground states built from contrasting distorted octahedral environments. This analysis fits a common nearest-neighbor in-plane exchange coupling (J=−8.6±0.3meV) between V3+ sites. The distorted local crystalline electric field combined with spin-orbit coupling provides the needed magnetic anisotropy for spatially long-ranged two-dimensional ferromagnetism in VI3.
|Number of pages||7|
|Journal||Physical Review B|
|Publication status||Published - 20 Jul 2021|