Phase diagram and spin-glass phenomena in electron-doped La1−xHfxMnO3 (0.05≤x≤0.3) manganite oxides J. Appl. Phys. 110, 113914 (2011) Rectifying characteristic of perovskite oxide La1.89Ce0.11CuO4/Ba0.5Sr0.5TiO3/La0.67Sr0.33MnO3 heterostructures J. Appl. Phys. 110, 103716 (2011) Strain modulated magnetization and colossal resistivity of epitaxial La2/3Ca1/3MnO3 film on BaTiO3 substrate Appl. Phys. Lett. 99, 092103 (2011) Magnetoresistance in epitaxial thin films of La0.85Ag0.15MnO3 produced by polymer assisted deposition Appl. Phys. Lett. 99, 083113 (2011) Additional information on J. Appl. Phys. Despite numerous attempts to explain the phenomenon of transport and magnetoresistance in manganites based on Jahn-Teller phonon coupling and double exchange mechanisms, satisfactory results could not be reached. The small polaron transport mechanism, based on the valence exchange arising from Madelung energy, is shown to account for the resistivity and magnetoresistance of the doped manganite La 2/3 Ca 1/3 MnO 3 in the ferromagnetic range. The transport equation for the correlated polaron based on the Holstein Hamiltonian shows the well known transition from the low temperature band to the localized polaron hopping conductivity at high temperature in agreement with experiment. The present attempt is to demonstrate that the complexity of the problem that involves the interplay between the spin and charge order on one hand and itinerant and localized behavior on the other for a simple ferromagnetic metal system of manganites is best described by the correlated small polaron model leaving the more complicated systems for future studies.

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The transport behavior of La1−xSrxMnO3 in the antiferromagnetic insulator, ferromagnetic insulator, and ferromagnetic metallic phases is shown to follow from the correlated polaron mechanism and a single transport equation accounts for the temperature dependence of resistivity for 0⩽x⩽0.40 in the 0–400K range. In the low temperature range zero-point lattice vibration plays a dominant role in the transport in the metallic phase.

The d 0 ferromagnetism in oxide films and nanoparticles without 3d elements and long-range magnetic order at concentrations of magnetic cations below the percolation limit with Curie temperature exceeding 300K is not explained on the present understanding of magnetism in solids. It is shown that these arise in nanostructure solids when two degenerate spin-polarized macro states of the system through coupling to zero-point phonon removes the degeneracy and increases the binding energy of the system by a small amount. The coupling through quantum tunnelling persists even in the presence of thermal fluctuations until the fraction of recoilless transitions in the ground state of the lattice vanishes. This accounts for its weak intensity, universality and existence over a wide temperature range.