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  Klyushina, E.; Islam, N.; Park, J.; Goremychkin, E.; Wheeler, E.; Klemke, B.; Lake, B.: Hamiltonian of the S=½ dimerized antiferromagnetic-ferromagnetic quantum spin-chain BaCu₂V₂O₈. Physical Review B 98 (2018), p. 104413/1-13

10.1103/PhysRevB.98.104413
Open Accesn Version

Abstract:
The novel quantum magnet BaCu₂V₂O₈ was recently discovered to be a rare physical realization of a one-dimensional antiferromagnetic - ferromagnetic dimerized chain which displays strongly correlated phenomena at elevated temperatures [\href{http://doi.org/10.1103/PhysRevB.93.241109}{Phys. Rev. B 93 241109(R) (2016)}]. This paper presents an extended study of the Hamiltonian of BaCu₂V₂O₈ at base temperature. Static susceptibility and inelastic neutron scattering data are compared to several theoretical models. An analytical relation for the dynamic structure factor of the complex unit cell of BaCu₂V₂O₈ is derived and used to identify the intrachain exchange paths. Further analysis using the first moment of the dynamic structure factor was employed to determine the exchange path responsible for the intradimer interaction. This analysis reveals that the dimer chain is formed by a dominant antiferromagnetic exchange iteraction J_intra=40.92~meV which is realized via the Cu-O-V(II)-O-Cu super-exchange path and a weak ferromagnetic coupling J_inter=-11.97~meV which arises within the copper-oxygen double-plaquettes.