Cupratelike electronic and magnetic properties of layered transition-metal difluorides from first-principles calculations

The electronic and magnetic properties of two isoelectronic layered transition-metal fluorides (AgF₂ and CuF₂) are considered in the context of high-temperature superconducting cuprates. The properties of AgF₂ are found to be cupratelike comprising a layered spin-1/2 system with strong p-d hybridization, and a large two-dimensional antiferromagnetic superexchange interaction, comparable to cuprates. Contrary to its Ag-counterpart, CuF₂ shows a small degree of p-d hybridization and a superexchange interaction one order of magnitude smaller than in cuprates. Within the Zaanen-Sawatzky-Allen model AgF₂ and CuF₂ could be classified as a charge-transfer and Mott-Hubbard insulator, respectively. As a consequence, this work further demonstrates the promise AgF₂ holds as a parent compound to a new class of Ag-based superconducting materials, whereas CuF₂ is not promising as a cuprate analog.