Multiplet effects in the electronic correlation of one-dimensional magnetic transition metal oxides on metals

Goikoetxea, Joseba; Friedrich, Christoph; Bihlmayer, Gustav; Blügel, Stefan; Arnau, A.; Blanco-Rey, M.

doi:10.1103/physrevb.106.035130

Cited by 2 publications

(1 citation statement)

References 44 publications

(67 reference statements)

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“…That is, the magnitude of the changes of the polarization are similar, and the major differences do not seem to come primarily from the improvements that HSE does by capturing the spin occupancy more precisely, but from its ability to capture slightly better some of those subtle structural changes created by the v O , which converge differently than the magnetism. A study of the possible magneto-electric coupling in these tentative multiferroic materials would require more sophisticated methods that could provide us with more precise U values for every vacancy distribution, for instance, by using cRPA calculations [80]. On the other hand, the use of oxygen deficiency as a trigger to multiferroic behavior requires us to classify accurately the metallic or semiconductor characteristics of systems that relax to energetically close GSs corresponding to different spin states.…”

Section: Discussionmentioning

confidence: 99%

Oxygen Deficiency and Migration-Mediated Electric Polarization in Magnetic Fe,Co-Substituted SrTiO3−δ

et al. 2022

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We use density functional theory (DFT) calculations to show that oxygen vacancies (vO) and mobility induce noncentrosymmetric polar structures in SrTi1−x−yFexCoyO3−δ (STFC, x=y=0.125) with δ={0.125,0.25}, enhance the saturation magnetization, and give rise to large changes in the electric polarization |ΔP|. We present an intuitive set of rules to describe the properties of STFC, which are based on the interplay between (Co/Fe)-vO defects, magnetic cation coordination, and topological vacancy disorder. STFC structures consist of layered crystals with sheets of linearly organized O4,5,6-coordinated Fe–Co pairs, sandwiched with layers of O5-coordinated Ti. (Co/Fe)-vO defects are the source of crystal distortions, cation off-centering and bending of the oxygen octahedra which, considering the charge redistribution mediated by vO and the cations’ electronegativity and valence states, triggers an effective electric polarization. Oxygen migration for δ=0.125 leads to |ΔP|>∼10 µC/cm2 due to quantum-of-polarization differences between δ=0.125 structures. Increasing the oxygen deficiency to δ=0.25 yields |ΔP|, the O migration of which resolved polarization for δ=0.25 is >∼3 µC/cm2. Magnetism is dominated by the Fe,Co spin states for δ=0.125, and there is a contribution from Ti magnetic moments (∼1 μB) for δ=0.25. Magnetic and electric order parameters change for variations of δ or oxygen migration for a given oxygen deficiency. Our results capture characteristics observed in the end members of the series SrTi(Co,Fe)O3, and suggest the existence of a broader set of rules for oxygen-deficient multiferroic oxides.

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Section: Discussionmentioning

confidence: 99%