The effect of Sr doping on the magnetic properties of Co perovskite

Within the unrestricted Hartree-Fock approximation and the real space recur sion method, we calculated the electronic structure of the La1 - xSrxCoO3 i n whole doping range 0.0 less than or equal to x less than or equal to 1.0. The low-spin (LS, t(2g)(6)e(g)(0)), the intermediate-spin (IS, t(2g)(5)e(g )(1)) and the high-spin (HS, t(2g)(4)e(g)(2)) states as well as their combi nations in the doubled cell were taken as the initial configurations. It is found that the system is a nonmagnetic low-spin state (t(2g)(6 - x)e(g)(0) ) for x less than or equal to 0.25 and a ferromagnetic intermediate-spin st ate (t(2g)(5)e(g)(1 - x)) for 0.25 < x less than or equal to 0.41. For 0.41 < x < 0.45, the ground state of the system is a IS-HS (t(2g)(5)e(g)(1 - x) -t(2g)(4)e(g)(2 - x)) nearest neighbor ferromagnetically ordered state, whi ch is followed by the KS state up to x = 1.0. The ground state proper-ties as a function of Sr doping are in accord with the experimental observations . (C) 1999 Elsevier Science B.V. All rights reserved.