  Spin-orbit coupled honeycomb magnets with the Kitaev interaction have
received a lot of attention due to their potential of hosting exotic quantum
states including quantum spin liquids. Thus far, the most studied Kitaev
systems are 4d/5d-based honeycomb magnets. Recent theoretical studies predicted
that 3d-based honeycomb magnets, including Na2Co2TeO6 (NCTO), could also be a
potential Kitaev system. Here, we have used a combination of heat capacity,
magnetization, electron spin resonance measurements alongside inelastic neutron
scattering (INS) to study NCTO's quantum magnetism, and we have found a
field-induced spin disordered state in an applied magnetic field range of 7.5 T
< B (vertical to b-axis) < 10.5 T. The INS spectra were also simulated to
tentatively extract the exchange interactions. As a 3d-magnet with a
field-induced disordered state on an effective spin-1/2 honeycomb lattice, NCTO
expands the Kitaev model to 3d compounds, promoting further interests on the
spin-orbital effect in quantum magnets.
