title: Orbital order and ferrimagnetic properties of Sr8CaRe3Cu4O24.
abstract: By means of the LSDA+U (local spin density approximation plus Hubbard 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 of ferrimagnetism with a net magnetic moment of 1.01 micro(B)/f.u., which is in good agreement with the experiment. It is the nonmagnetic 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.
authors.affiliation: Computational Materials Science Center, National Institute for Materials Science, Tsukuba 305-0047, Japan.
authors.forename: Xiangang
authors.initials: X
authors.lastname: Wan
authors.forename: Masanori
authors.initials: M
authors.lastname: Kohno
authors.forename: Xiao
authors.initials: X
authors.lastname: Hu