Frustrated diamond-chain quantum $XXZ$ Heisenberg antiferromagnet in a   magnetic field
  We consider the antiferromagnetic spin-1/2 $XXZ$ Heisenberg model on a frustrated diamond-chain lattice in a $z$- or $x$-aligned external magnetic field. We use the strong-coupling approach to elaborate an effective description in the low-temperature strong-field regime. The obtained effective models are spin-1/2 $XY$ chains which are exactly solvable through the Jordan-Wigner fermionization. We perform exact-diagonalization studies of the magnetization curves to test the quality of the effective description. The results may have relevance for the description of the azurite spin-chain compound. 
Johannes Richter, Olesia Krupnitska, Taras Krokhmalskii, Oleg Derzhko
cond-mat.str-el