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arXiv · 1006.5811

Multiple double-exchange mechanism by Mn$^{2+}$-doping in manganite compounds

P. Orgiani·A. Galdi·C. Aruta·V. Cataudella·G. De Filippis·C. A. Perroni·V. Marigliano Ramaglia·R. Ciancio·N. B. Brookes·M. Moretti Sala·G. Ghiringhelli·L. Maritato
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Abstract

Double-exchange mechanisms in RE$_{1-x}$AE$_{x}$MnO$_{3}$ manganites (where RE is a trivalent rare-earth ion and AE is a divalent alkali-earth ion) relies on the strong exchange interaction between two Mn$^{3+}$ and Mn$^{4+}$ ions through interfiling oxygen 2p states. Nevertheless, the role of RE and AE ions has ever been considered "silent" with respect to the DE conducting mechanisms. Here we show that a new path for DE-mechanism is indeed possible by partially replacing the RE-AE elements by Mn$^{2+}$-ions, in La-deficient La$_{x}$MnO$_{3-\delta}$ thin films. X-ray absorption spectroscopy demonstrated the relevant presence of Mn$^{2+}$ ions, which is unambiguously proved to be substituted at La-site by Resonant Inelastic X-ray Scattering. Mn$^{2+}$ is proved to be directly correlated to the enhanced magneto-transport properties because of an additional hopping mechanism trough interfiling Mn$^{2+}$-ions, theoretically confirmed by calculations within the effective single band model. The very idea to use Mn$^{2+}$ both as a doping element and an ions electronically involved in the conduction mechanism, has never been foreseen, revealing a new phenomena in transport properties of manganites. More important, such a strategy might be also pursed in other strongly correlated materials.

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P. Orgiani, A. Galdi, C. Aruta, V. Cataudella, G. De Filippis, C. A. Perroni, V. Marigliano Ramaglia, R. Ciancio, N. B. Brookes, M. Moretti Sala, G. Ghiringhelli, L. Maritato. 2010-06-30. Multiple double-exchange mechanism by Mn$^{2+}$-doping in manganite compounds. https://doi.org/10.1103/physrevb.82.205122

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