Tuning of magnetic ground state of the spin-1/2 square-lattice compound Zn2VO(PO4)2 through chemical substitution

Using first-principles density-functional-theory-based calculations, we derive the low-energy spin model of the compound Zn2VO(PO4)(2), and 1/4th Ti-substituted compound Zn8TiV3O4(PO4)(8) which is yet to be synthesized. We compute the thermodynamics properties of the proposed spin models by the quantum Monte Carlo technique. For the pristine compound Zn2VO(PO4)(2) our computed susceptibility is found to be in good agreement with the available experimental data and is in accordance with the earlier proposed spin model of the spin-1/2 antiferromagnetic square lattice. Upon Ti substitution, which may be viewed as 1/4-spin depletion, the two-dimensional antiferromagnetic square-lattice behavior of the parent compound is found to be altered significantly, giving rise to spin-gap behavior. We hope that our work will stimulate further experimental studies on this compound. DOI: 10.1103/PhysRevB.87.054431