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TT: Fachverband Tiefe Temperaturen
TT 27: CE: Poster Session
TT 27.75: Poster
Wednesday, March 24, 2010, 14:00–18:00, Poster D1
Hole induced spin polarons in LaCoO3 — •A. Alfonsov1, E. Vavilova1,2, V. Kataev1, A. Podlesnyak3, D.I. Khomskii4, and B. Büchner1 — 1IFW Dresden, D-01171 Dresden, Germany — 2Zavoisky Physical Technical Institute, RAS, 420029 Kazan, Russia — 3Oak Ridge National Laboratory, P.O. BOX 2008 MS6494 Oak Ridge TN 37831-6494, USA — 4II. Physikalisches Institut, Universität zu Köln, 50937 Köln, Germany
We report a comparative high field electron spin- (ESR), nuclear magnetic resonance (NMR) and static magnetization study of lightly hole-doped samples of La0.998Sr0.002CoO3 and La0.998Ca0.002CoO3. We have shown before [1] that small Sr doping of LaCoO3 yields the spin-state polaron with a big spin value and large spin orbital coupling. The Ca2+ ion, in contrast to the Sr2+ ion, has almost the same ionic radii as the La3+ ion. Therefore, the substitution of Ca for La provides mainly a hole to the system without creating a sizeable crystal field distortion around the substituted Ca ion. This difference enables us to ascertain the roles of the introduced hole and the created crystal field distortion in the formation of the spin polarons. The data obtained on Ca and Sr doped LaCoO3 samples provide experimental evidence that the introduced hole indeed plays the main role. We discuss a model of the formation of big spin polarons in LaCoO3 due to a very small hole doping.
[1] A. Podlesnyak et al., Phys. Rev. Lett. 101, 247603 (2008)