Magnetic susceptibility of frustrated spin-s J1-J2 quantum Heisenberg   magnets: High-temperature expansion and exact diagonalization data
  Motivated by recent experiments on low-dimensional frustrated quantum magnets with competing nearest-neighbor exchange coupling J1 and next nearest-neighbor exchange coupling J2 we investigate the magnetic susceptibility of two-dimensional J1-J2 Heisenberg models with arbitrary spin quantum number s. We use exact diagonalization and high-temperature expansion up to order 10 to analyze the influence of the frustration strength J2/J1 and the spin quantum number s on the position and the height of the maximum of the susceptibility. The derived theoretical data can be used to get information on the ratio J2/J1 by comparing with susceptibility measurements on corresponding magnetic compounds. 
J. Richter, A. Lohmann, H.-J. Schmidt, D.C. Johnston
cond-mat.str-el