Magnetic ground state of the Kitaev Na₂Co₂TeO₆ spin liquid candidate

As a candidate Kitaev material, Na2Co2TeO6 exhibits intriguing magnetism on a honeycomb lattice that is believed to be C-3 symmetric. Here we report a neutron diffraction study of high-quality single crystals under a-axis magnetic fields. Our data support the less common notion of a magnetic ground state that corresponds to a triple-q magnetic structure with C-3 symmetry, rather than the multidomain zigzag structure typically assumed in prototype Kitaev spin liquid candidates. In particular, we find that the field is unable to repopulate the supposed zigzag domains, where the only alternative explanation is that the domains are strongly pinned by hitherto unidentified structural reasons. If the triple-q structure is correct, then this requires reevaluation of many candidate Kitaev materials. We also find that fields beyond about 10 Tesla suppress the long-range antiferromagnetic order, allowing magnetic behavior to emerge different from that expected for a spin liquid.