Europhys. Lett.
Volume 68, Number 3, November 2004
Page(s) 453 - 459
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 13 October 2004
Europhys. Lett., 68 (3), pp. 453-459 (2004)
DOI: 10.1209/epl/i2004-10233-3

Spin-polarized oxygen hole states in cation-deficient $\chem{La}$ 1-x $\chem{Ca}$ x $\chem{MnO}$ $_{3+\delta}$

G. Papavassiliou1, M. Pissas1, M. Belesi1, M. Fardis1, M. Karayanni1, J. P. Ansermet2, 3, D. Carlier3, C. Dimitropoulos3 and J. Dolinsek4

1  Institute of Materials Science, NCSR Demokritos 153 10 Aghia Paraskevi, Attiki, Greece
2  Department of Physics, University of Illinois - Urbana, IL 1801, USA
3  Institut de Physique Experimentale, EPFL-PH-Ecublens 1015-Lausanne, Switzerland
4  Josef Stefan Institute - Jamova 39, 61111 Ljubljana, Slovenia

received 12 May 2004; accepted in final form 15 September 2004
published online 13 October 2004

We report on NMR evidence about a novel effect in $\chem{La}$ 1-x $\chem{Ca}$ x $\chem{MnO}$ $_{3+\delta}$ systems with cation deficience. We show that in the low- $\chem{Ca}$-doping regime, these systems exhibit a very strong hyperfine field at certain $\chem{La}$ nuclear sites, which is not present in the stoichiometric compounds. Comparison of our NMR results with recent X-ray absorption data at the $\chem{Mn}$ K-edge, suggests the formation of a spin-polarized hole arrangement on the 2p oxygen orbitals as the origin of this effect.

75.47.Lx - Manganites.
76.60.-k - Nuclear magnetic resonance and relaxation.
75.47.Gk - Colossal magnetoresistance.

© EDP Sciences 2004