2017
DOI: 10.1103/physrevmaterials.1.054403
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Ferromagnetic and insulating behavior of LaCoO3 films grown on a (001) SrTiO3 substrate: A simple ionic picture explained ab initio

Abstract: Ferromagnetic and insulating behavior of LaCoO 3 films grown on a (001) SrTiO 3 substrate. A simple ionic picture explained ab initio. This paper shows that the oxygen vacancies observed experimentally in thin films of LaCoO3 subject to tensile strain are thermodynamically stable according to ab initio calculations. By using DFT calculations, we show that oxygen vacancies on the order of 6 % forming chains perpendicular to the (001) direction are more stable than the stoichiometric solution. These lead to magn… Show more

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Cited by 5 publications
(3 citation statements)
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“…[26] for a detailed discussion). The formation of stripe domains at the surface of tensilestrained LCO films has been observed experimentally [45,78] and confirmed in numerical calculations [78,79], making thus plausible that the LCO surface exhibits 1D FM ordering as well. Although we cannot unambiguously distinguish between the 1D and 2D FM cases from the magnetoresistance measurements, our analysis suggests that the surface Co ions might exhibit both contributions because the temperature dependence is fitted best by the model of spin ladders [blue line, Fig.…”
supporting
confidence: 57%
“…[26] for a detailed discussion). The formation of stripe domains at the surface of tensilestrained LCO films has been observed experimentally [45,78] and confirmed in numerical calculations [78,79], making thus plausible that the LCO surface exhibits 1D FM ordering as well. Although we cannot unambiguously distinguish between the 1D and 2D FM cases from the magnetoresistance measurements, our analysis suggests that the surface Co ions might exhibit both contributions because the temperature dependence is fitted best by the model of spin ladders [blue line, Fig.…”
supporting
confidence: 57%
“…Our optimization resulted in c opt = 3.96 Å, which is larger than in the stoichiometric case and related to the partial Co reduction. We confirmed this expansion by additional simulations employing the Vienna Ab initio simulation package [57][58][59] (see Supplemental Material), but note that the concentration and geometry of the oxygen vacancies 60 as well as the choice of the exchangecorrelation functional may impact the cell height. The planar La-La distances are contracted around the CoO 6 octahedra and expanded around the CoO 4 tetrahedra [i.e., the oxygen vacancy (100) planes] and amount to 3.63/3.63/4.45 Å, which are close to the measured values 3.61/3.61/4.54 Å.…”
Section: Electronic Properties and Orbital Ordersupporting
confidence: 58%
“…1(a)-1(d). Another explanation for the ferromagnetic ordering in films was proposed by Fumega and Pardo, where they suggested the presence of ordered oxygen vacancies (i.e., Co 2+ ions), which in turn stabilize the ferromagnetic ordering [19,20]. This would imply that Co 2+ ions are involved in a double-exchange-type interaction between Co 3+ and Co 2+ .…”
Section: Introductionmentioning
confidence: 96%