Papavassiliou, G.Pissas, M.Belesi, M.Fardis, M.Karayanni, M.Ansermet, J. P.Carlier, D.Dimitropoulos, C.Dolinsek, J.2010-03-232010-03-232010-03-23200410.1209/epl/i2004-10233-3https://infoscience.epfl.ch/handle/20.500.14299/48556WOS:000225057100020We report on NMR evidence about a novel effect in La1-xCa xMnO3+δ 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.text::journal::journal article::research article