New Diamond-lattice Antiferromagnet CaCo₂TeO₆

Diamond-lattice Heisenberg antiferromagnets provide an exciting pathway for realizing novel spin physics. Most of the studies, however, have been limited to AB₂X₄ spinels, wherein the magnetic ion forming an ideal diamond lattice experiences a tetrahedral ligand field. This limits the control of splitting of d-orbitals, electronic structures, and ligand effects, thus the tunability of competing exchange interactions at the atomic level.

To address this, we create a new diamond-lattice Heisenberg antiferromagnet, CaCo₂TeO₆, with two distinct Co²⁺ ions in an octahedral ligand field. This material exhibits antiferromagnetic transitions at 14 and 16 K, nonlinear optical responses arising from a finite magnetic dipole, and non-colinear magnetic ground state. More details about the structural and physical properties supported by the spin-polarized band structure and exchange interactions will be discussed in the talk.