Uncovering Complex Magnetism in the Buckled Honeycomb Magnet Co₂SeO₃Cl₂

Buckled honeycomb magnets with J_eff =1/2 provide a fertile ground for unconventional states of matter, such as strong quantum fluctuations and spin liquids . Unlike conventional honeycomb lattices, where competing interactions are dominated by nearest and next-nearest-neighbor interactions, buckled honeycomb lattices allow bond-dependent anisotropic interactions that disfavor conventional long-range magnetic ordering. We discover a new magnet Co₂SeO₃Cl_2, in which the Co²⁺ ions form a buckled honeycomb lattice. Magnetization measurements reveal competing ferromagnetic and antiferromagnetic interactions, while the heat capacity data indicate significant residual magnetic entropy. Band structure calculations provide insights into how the electronic structure of the material determines its physical properties. These results enable a new realization of the complex buckled honeycomb system Co₂SeO₃Cl₂ with strong quantum fluctuations. Further insights and detailed results will be discussed in the talk.