Oxidation states of Mn and Fe in various compound oxide systems

Schmid, H.; Mader, W.

doi:10.1016/j.micron.2005.12.004

Cited by 263 publications

(244 citation statements)

References 15 publications

Supporting

Mentioning

201

Contrasting

Unclassified

Order By: Relevance

“…[33][34][35] The decreased relative intensity of the L 2 edge for Gd-capped samples is consistent with this interpretation. [33][34][35] In agreement with bulk magnetometry, XMCD shows reduced magnetization associated with the presence of a Gd capping layer. Specifically, the integrated dichroism under the Mn L3 edge corresponds to a 21% reduction in LSMO magnetization for the 0.8 nm Gd-capped sample, larger than the 9% average magnetization reduction obtained from VSM measurements.…”

supporting

confidence: 81%

“…Based on the position and increased intensity of this L 3 shoulder peak, we conclude that additional oxygen vacancies are formed and a significant fraction of the interfacial Mn is in the 2þ valence state. [31][32][33][34][35] The main L 3 peak (E % 641 eV) is also shifted to slightly lower energy, indicating movement from mixed Mn 3þ and Mn 4þ to pure Mn 3þ . [33][34][35] The decreased relative intensity of the L 2 edge for Gd-capped samples is consistent with this interpretation.…”

mentioning

confidence: 99%

“…[31][32][33][34][35] The main L 3 peak (E % 641 eV) is also shifted to slightly lower energy, indicating movement from mixed Mn 3þ and Mn 4þ to pure Mn 3þ . [33][34][35] The decreased relative intensity of the L 2 edge for Gd-capped samples is consistent with this interpretation. [33][34][35] In agreement with bulk magnetometry, XMCD shows reduced magnetization associated with the presence of a Gd capping layer.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Reversible control of magnetism in La0.67Sr0.33MnO3 through chemically-induced oxygen migration

Grutter

Gilbert

Alaan

et al. 2016

Applied Physics Letters

View full text Add to dashboard Cite

We demonstrate reversible control of magnetization and anisotropy in La0.67Sr0.33MnO3 films through interfacial oxygen migration. Gd metal capping layers deposited onto La0.67Sr0.33MnO3 leach oxygen from the film through a solid-state redox reaction to form porous Gd2O3. X-ray absorption and polarized neutron reflectometry measurements show Mn valence alterations consistent with high oxygen vacancy concentrations, resulting in suppressed magnetization and increased coercive fields. Effects of the oxygen migration are observed both at the interface and also throughout the majority of a 40 nm thick film, suggesting extensive diffusion of oxygen vacancies. After Gd-capped La0.67Sr0.33MnO3 is exposed to atmospheric oxygen for a prolonged period of time, oxygen diffuses through the Gd2O3 layer and the magnetization of the La0.67Sr0.33MnO3 returns to the uncapped value. These findings showcase perovskite heterostructures as ideal candidates for developing functional interfaces through chemically-induced oxygen migration.

show abstract

supporting

confidence: 81%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Reversible control of magnetism in La0.67Sr0.33MnO3 through chemically-induced oxygen migration

Grutter

Gilbert

Alaan

et al. 2016

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…The position of the Mn L 3 edge is well known to be related to the Mn oxidation state. [12][13][14] In Fig. 3͑b͒ we report the Mn L 3 edge position along the layer ͑from interface to free surface͒ for ͑001͒ and ͑110͒ layers of different thicknesses.…”

mentioning

confidence: 99%

Effects of thickness on the cation segregation in epitaxial (001) and (110) La2/3Ca1/3MnO3 thin films

Estradé

Rebled

Arbiol

et al. 2009

Applied Physics Letters

View full text Add to dashboard Cite

Electron-energy-loss spectroscopy is used to map composition and electronic states in epitaxial La 2/3 Ca 1/3 MnO 3 ͑LCMO͒ films of various thicknesses grown on SrTiO 3 ͑001͒ and ͑110͒ substrates. For relatively thick films ͑Ն20 nm͒, epitaxial tensile strain in ͑001͒ films promotes a compositional La/Ca gradient across the film thickness, being the interface La rich, while the relaxed ͑110͒ films are chemically homogeneous. In contrast, much thinner ͑001͒ and ͑110͒ LCMO films display a different La/Ca distribution, being La rich at the free surface. The observed distinct thickness-dependent composition gradient behavior reflects a balance between strain-induced elastic energy minimization and kinetic effects during growth. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3211130͔Mixed-valence ferromagnetic manganite films have been the object of much attention in recent years due to their potential applications in spintronics. 1,2 However, expectations have been lowered by the negligible room-temperature magnetoresistance observed in tunnel junctions. 3 Although the reasons for this behavior are not yet fully known, it has been suggested that they may be linked to electronic phase separation. 4 Whether the latter is a pure electronic effect or related to inhomogeneous chemical distributions can be suitably explored by electron energy-loss spectroscopy ͑EELS͒. For instance, electronic states can be mapped out by direct determination of local Mn oxidation state at the nanometric scale. [5][6][7][8] On the other hand, mappings of the chemical composition can be achieved offering chemical information at the nanometric scale [5][6][7][8][9] We recently reported 8 a comparative characterization, both from the microstructural and chemical points of view, of relatively thick ͑ϳ80 nm͒ LCMO layers grown on STO in order to determine which differences accounted for the fact that ͑110͒ LCMO films display enhanced magnetic properties when compared to their ͑001͒ counterparts. While homogeneous chemical composition was associated to the contribution of plastic defects as strain-relieve mechanism in the more relaxed ͑110͒ films, a Ca 2+ ion migration toward free surface, and the concomitant Mn m+ oxidation state variation was observed in the more stressed ͑001͒ films.In this letter, we have extended the characterization of the microstructure, local stoichiometry variations, and Mn oxidation state of ͑001͒ and ͑110͒ LCMO films within a range of layer thicknesses between 3.5 and 40 nm. The results confirm the same trend for LCMO films with t ϳ 40 nm as those with t ϳ 80 nm previously reported. 8 However, most importantly, we assess that for ultrathin LCMO films ͑t Ͻ 20 nm͒, a new scenario is revealed with significant differences regarding cation distribution across the film in comparison with thicker layers, while keeping an orthorhombic crystalline phase in contrast with structural changes reported by Qin et al. 10 The ͑001͒ and ͑110͒ LCMO films with thicknesses ͑t͒ ranging from 3.5 to 82 nm were grown by rf sputtering at 8...

show abstract

“…Reidl et al (2006) found the Walsh-Dray method to be most precise in estimating the continuum background when analyzing Mn(III) 2 O 3 , Mn(IV)O 2 and BaMn(VI)O 4 . Schmidt and Mader (2006) compared the relative precision of the whiteline intensity ratio method as compared to the changes in the absolute energy positions of the peaks (∆E(L 2 -L 3 )). They concluded that although ∆E(L 2 -L 3 ) changes systematically with mean valence, it has a greater error.…”

Section: Quantification Of Valence By L 23 -Elnesmentioning

confidence: 99%