Spin-1/2 XXZ diamond chain within the Jordan-Wigner fermionization   approach
  The spin-1/2 XXZ diamond chain is considered within the Jordan-Wigner fermionization. The fermionized Hamiltonian contains the interacting terms which are treated within the Hartree-Fock approximation. We obtain the ground-state magnetization curve of the model for some particular cases and compare the results with the exact diagonalization data for finite chains of 30 spins and known exact results. We also analyze the validity of the suggested approximation. 
Taras Verkholyak, Jozef Strecka, Michal Jascur, Johannes Richter
cond-mat.str-el