گذار فاز فرومغناطيسي و تبادل دوتايي الكترونها در تركيباتRU1-XCrxCaO3

Ferromagnetic transition and double exchange of electrons in the Ru1-xCrxCa03 compounds

We have investigated the electronic structure of Ru1-xCrxCa03 using the full potential linearized augmented plane wave method within the local spin density approximation. We have obtained the spin magnetic moment centered at Ru sites from LSDA calculation. The Ru magnetic moment is consistent with the experimental estimates and is lower than the t32gft12gi electronic configuration. Cr decreases the extension of the 4d orbitals and increases the exchange coupling beween electrons which may increase the magnetic moment further. Parameters of the electron-electron interaction for the RuM03 and CrM03 with M=Ca have been estimated by the standard LSDA-constraint technique. These calculations show that both the DOS and effective Coulomb interaction increase with the increase of Cr content.