Role of chemical pressure on the electronic and magnetic properties of the spin-1/2 kagome mineral averievite

The electronic and magnetic properties of the S=1/2 kagome mineral averievite Cu₅V₂O₁₀(CsCl) and its phosphate analog Cu₅P₂O₁₀(CsCl) have been investigated using density functional theory calculations. The crystal structure of these compounds contains Cu²⁺ kagome layers sandwiched between Cu²⁺-V⁵⁺/Cu²⁺-P⁵⁺ honeycomb layers with the Cu atoms of neighboring kagome and honeycomb planes forming pyrochlore slabs. The induced chemical pressure effect upon substitution of V by P causes significant changes in the electronic and magnetic properties. Our calculations show that the in-plane antiferromagnetic (AFM) nearest-neighbor coupling in the kagome layers remains similar in both V- and P-based materials. In contrast, the inter-plane AFM coupling between kagome and honeycomb layers becomes five times larger in P-variant, increasing the degree of magnetic frustration in the constituting pyrochlore slabs. By substituting honeycomb Cu²⁺ with Zn²⁺, the kagome S=1/2 planes can be isolated and become the only magnetically active ones, making Zn-substituted averievite a promising candidate for quantum spin liquid behavior.