Theoretical Study on Ferrimagnetism of New Material Sr8CaRe3Cu4O24

Magnetic properties of the recently-discovered new phase of Sr 8 CaRe 3 Cu 4 O 24 are investigated by means of a quantum Monte Carlo method, the Green function method and the local spin-density approximation plus Hubbard- U term (LSDA+U) method. We derive an effective model for magnetic properties of this material based on the LSDA+U calculation. The resultant effective model is a spin-alternating Heisenberg model in three dimensions. We investigate thermodynamic properties of this effective model by a quantum Monte Carlo method and the Green function method. Numerical results are quantitatively consistent with experimental results of Sr 8 CaRe 3 Cu 4 O 24 . We further make some predictions for this material through analysis of the effective model.