Disproportionation and electronic phase separation in parent manganite LaMnO_3

Abstract

Nominally pure undoped parent manganite LaMnO_3 exhibits a puzzling behavior inconsistent with a simple picture of an A-type antiferromagnetic insulator (A-AFI) with a cooperative Jahn-Teller ordering. We do assign its anomalous properties to charge transfer instabilities and competition between insulating A-AFI phase and metallic-like dynamically disproportionated phase formally separated by a first-order phase transition at T_{disp}=T_{JT}\approx 750 K. The unconventional high-temperature phase is addressed to be a specific electron-hole Bose liquid (EHBL) rather than a simple "chemically" disproportionated R(Mn^{2+}Mn^{4+})O_3 phase. New phase does nucleate as a result of the charge transfer (CT) instability and evolves from the self-trapped CT excitons, or specific EH-dimers, which seem to be a precursor of both insulating and metallic-like ferromagnetic phases observed in manganites. We arrive at highly frustrated system of triplet (e_g^2)^3A_{2g} bosons moving in a lattice formed by hole Mn^{4+} centers. Starting with different experimental data we have reproduced a typical temperature dependence of the volume fraction of high-temperature mixed-valent EHBL phase. We argue that a slight nonisovalent substitution, photo-irradiation, external pressure or magnetic field gives rise to an electronic phase separation with a nucleation or an overgrowth of EH-droplets. Such a scenario provides a comprehensive explanation of numerous puzzling properties observed in parent and nonisovalently doped manganite LaMnO_3 including an intriguing manifestation of superconducting fluctuations.

20 pages, 8 figures

References in corpus (2)

• Modelling colossal magnetoresistance manganites
• Dielectric anomaly at the orbital order-disorder transition in LaMnO_(3+delta)

Cited by in corpus (13)

• Interplay of p-d and d-d charge transfer transitions in rare-earth perovskite manganites
• What is the true charge transfer gap in parent insulating cuprates?
• Multiple double-exchange mechanism by Mn${}^{2+}$-doping in manganite compounds
• Electron-Lattice Interplays in LaMnO3 from Canonical Jahn-Teller Distortion Notations
• Coexistence of coupled magnetic phases in epitaxial TbMnO3 films revealed by ultrafast optical spectroscopy
• Valence-skipping and negative-U in the d-band from repulsive local Coulomb interaction
• Korringa-like relaxation in the high-temperature phase of A-site ordered YBaMn2O6
• Microscopic mechanisms of spin-dependent electric polarization in 3d oxides
• Perspectives of the disproportionation driven superconductivity in strongly correlated 3d compounds
• Electric field driven destabilization of the insulating state in nominally pure LaMnO3
• Topological structures in unconventional scenario for 2D cuprates
• Pseudospin S=1 description of the cuprate complexity: the charge triplets model
• Insulator-bad metal transition in RNiO${}_3$ nickelates beyond Hubbard model and density functional theory