Jeff = 1/2 Diamond Magnet CaCo2TeO6: Reimagining Frontiers of Spin Liquids and Quantum Functions

Diamond-lattice magnets, characterized by a framework of corner-sharing tetrahedra of magnetic cations, offer compelling avenues for realizing novel states of matter, with potential utilities in quantum technologies. However, focusing exclusively on spinels with Td-site magnetic ions limits the tunability of competing Heisenberg interactions at comparable energy scales, hindering the ability to harness many-body electronic states and making the realization of Jeff = 1/2 and quantum spin liquids less accessible. We realize CaCo2TeO6—a new Jeff = 1/2 diamond magnet featuring Oh-Co2+. This material displays enhanced competing Heisenberg exchange interactions, strong quantum fluctuations, and a field-induced quantum spin disordered state above 20 T. The results highlight the tantalizing physical and functional aspects of CaCo2TeO6, enabling a new pathway toward spin liquids and emergent quantum functionalities.