2004/05/31 by Xiangang Wan, Masanori Kohno, Xiao Hu
Physics and Astronomy · #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.94.087205
published as Physical Review Letters 94, 087205 (2005) · 8 pages and 5 figure
arxiv created 2004/05/31 · arxiv updated 2009/12/01
By means of the LSDA+U method and the Green function method, we investigate the electronic and magnetic properties of the new material of Sr8CaRe3Cu4O24. Our LSDA+U calculation shows that this system is an insulator with a net magnetic moment of 1.01 μ\rm B/f.u., which is in good agreement with the experiment. Magnetic moments are mainly located at Cu atoms, and the magnetic moments of neighboring Cu sites align anti-parallel. It is the non-magnetic Re atoms that induce an orbital order of d electrons of Cu atoms, which is responsible for the strong exchange interaction and the high magnetic transition temperature. Based on the LSDA+U results, we introduce an effective model for the spin degrees of freedom, and investigate the finite-temperature properties by the Green function method. The obtained results are consistent with the experimental results, indicating that the spin-alternating Heisenberg model is suitable for this compound.