Quasi-2D J1–J2 antiferromagnet Zn2VO(PO4)2 and its Ti-substituted derivative: A spin-wave analysis

In this study, we present non-linear spin wave analysis of a quasi-2D spin-12J1–J2 antiferromagnet at the parameter regime relevant for the recently studied compound Zn2VO(PO4)2. We obtain the temperature dependence of the spin wave energy, susceptibility and magnetization using Green's function technique and Tyablikov's decoupling or Hartree–Fock factorization. The comparison of our numerical results with the experimental findings is discussed. Magnetic structure factor is calculated and compared with powder neutron diffraction data. We also study the spin wave behavior of the compound Zn2Ti0.25V0.75O(PO4)2 obtained by partial chemical substitution of Ti at V sites of the compound Zn2VO(PO4)2 [Kanungo, et al., Phys. Rev. B 87 (2013) 054431]. Due to the superlattice structure of the spin lattice, the substituted compound possesses multiple spin wave modes. The spin wave analysis confirms the quasi-1D nature of the substituted system.