Exchange energies of Kapellasite from high-temperature series analysis   of the kagome lattice J1-J2-Jd-Heisenberg model
  We present a method to build magnetic models for insulators based on high-temperature expansions by fitting both the magnetic susceptibility and the low temperature specific heat data. It is applied to the frustrated magnet kapellasite (Cu3Zn(OH)6Cl2) with the J1-J2-Jd-Heisenberg model on the kagome lattice. Experimental data are reproduced with a set of "competing" exchange energies closed to J1 = -12K, J2= -4K and Jd=15.6K, where Jd is the third neighbor exchange energy across the hexagon. Strong constrains between these exchange energies are established. These values confirm the results of B. F{\aa}k et al. (Phys. Rev. Lett., 109, 037208 (2012)) regarding the location of kapellasite in the {\it cuboc2} phase of the Heisenberg model. The quality and limits of this modeling are discussed. 
B. Bernu, C. Lhuillier, E. Kermarrec, F. Bert, P. Mendels, R. H.   Colman and A. S. Wills
cond-mat.str-el