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Spin-polarized oxygen hole states in cation deficient La(1-x)CaxMnO(3+delta)

G. Papavassiliou·M. Pissas·M. Belesi·M. Fardis·J. P. Ansermet·D. Carlier·C. Dimitropoulos·J. Dolinsek
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Abstract

When holes are doped into a Mott-Hubbard type insulator, like lightly doped manganites of the La(1-x)CaxMnO3 family, the cooperative Jahn-Teller distortions and the appearance of orbital ordering require an arrangement of Mn(3+)/Mn(4+) for the establishment of the insulating canted antiferromagnetic (for x<=0.1), or of the insulating ferromagnetic (for 0.1<x<= 0.2) ground state. In the present work we provide NMR evidence about a novel and at the same time puzzling effect in La(1-x)CaxMnO(3+delta) systems with cation deficience. We show that in the low Ca-doping regime, these systems exhibit a very strong hyperfine field at certain La nuclear sites, which is not present in the stoichiometric compounds. Comparison of our NMR results with recent x-ray absorption data at the Mn K edge, suggests the formation of a spin-polarized hole arrangement on the 2p oxygen orbitals as the origin of this effect.

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G. Papavassiliou, M. Pissas, M. Belesi, M. Fardis, J. P. Ansermet, D. Carlier, C. Dimitropoulos, J. Dolinsek. 2003-10-06. Spin-polarized oxygen hole states in cation deficient La(1-x)CaxMnO(3+delta). https://doi.org/10.1209/epl%2Fi2004-10233-3

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