Charge order and the metal-insulator transitions inA1/2A1/2′MnO3

Michel van Veenendaal, A. J. Fedro
1999 Physical Review B (Condensed Matter)  
An interpretation is given for the metal-insulator transitions occurring in A 1/2 A 1/2 Ј MnO 3 using the doubleexchange model but including the coupling of the electron to the Jahn-Teller distortions and a finite Coulomb interaction between electrons in the twofold degenerate e g orbitals. We find that, whereas the ferromagnetic state is metallic, the insulating state is polaronic. As one lowers the temperature, a transition from the ferromagnetic state to the CE phase is observed, which is,
more » ... served, which is, due to the strong phonon renormalization of the bandwidth, accompanied by a change in resistivity of several orders of magnitude. In order to obtain the observed magnetic structure, i.e., CE type, it is essential to include the lowering of the on-site energy due to polaronic self-energy effects. We present a way of building the charge-ordered magnetic structures out of small units of a "localized" 3z 2 Ϫr 2 polaron with four antiferromagnetic and two ferromagnetic neighboring t 2g core spins.
doi:10.1103/physrevb.59.15056 fatcat:bdmw3e3ej5dpdaydngoi745cuq