Charge order and the metal-insulator transitions in A{sub 1/2}A{sub 1/2}{sup {prime}}MnO{sub 3}
- Northern Illinois University, De Kalb, Illinois 60115 (United States)
An interpretation is given for the metal-insulator transitions occurring in A{sub 1/2}A{sub 1/2}{sup {prime}}MnO{sub 3} using the double-exchange 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{sub 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, 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 {open_quotes}localized{close_quotes} 3z{sup 2}{minus}r{sup 2} polaron with four antiferromagnetic and two ferromagnetic neighboring t{sub 2g} core spins. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 345430
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 59, Issue 23; Other Information: PBD: Jun 1999
- Country of Publication:
- United States
- Language:
- English
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