Field-induced quantum spin disordered state in spin-1/2 honeycomb magnet Na2Co2TeO6 with small Kitaev interaction

Spin-orbit coupled honeycomb magnets with the Kitaev interaction have caught lots of attention since they host exotic physical properties, including the long-sought quantum spin-liquid (QSL) state. So far, the most studied Kitaev systems are 4d/5d-based honeycomb magnets. Meanwhile, recent theoretical studies predicted that 3d-based honeycomb magnets, including Na2Co2TeO6 (NCTO), could also be a potential Kitaev system. To explore this possibility, we studied the magnetic phase diagram and spin-wave excitations of NCTO. While a relatively small K interaction is obtained in NCTO, it is surprising to observe a field-induced spin disordered state within applied magnetic field of 7.5 T < B (perpendicular to b-axis) < 10.5 T. Therefore, NCTO is a unique example to exhibit field-induced disordered state on effective spin-1/2 honeycomb lattice but with small K interaction, which does not fit to existing theoretical frame and calls for future studies.