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Orbital reconstruction in nonpolar tetravalent transition-metal oxide layers.

Bogdanov NA, Katukuri VM, Romhányi J, Yushankhai V, Kataev V, Büchner B, van den Brink J, Hozoi L - Nat Commun (2015)

Bottom Line: We resolve in this regard the d-level structure of layered Sr2IrO4 by electron spin resonance.This implies that the iridium d levels are inverted with respect to their normal ordering.State-of-the-art electronic-structure calculations confirm the level switching in Sr2IrO4, whereas we find them in Ba2IrO4 to be instead normally ordered.

View Article: PubMed Central - PubMed

Affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany.

ABSTRACT
A promising route to tailoring the electronic properties of quantum materials and devices rests on the idea of orbital engineering in multilayered oxide heterostructures. Here we show that the interplay of interlayer charge imbalance and ligand distortions provides a knob for tuning the sequence of electronic levels even in intrinsically stacked oxides. We resolve in this regard the d-level structure of layered Sr2IrO4 by electron spin resonance. While canonical ligand-field theory predicts g//-factors less than 2 for positive tetragonal distortions as present in Sr2IrO4, the experiment indicates g// is greater than 2. This implies that the iridium d levels are inverted with respect to their normal ordering. State-of-the-art electronic-structure calculations confirm the level switching in Sr2IrO4, whereas we find them in Ba2IrO4 to be instead normally ordered. Given the nonpolar character of the metal-oxygen layers, our findings highlight the tetravalent transition-metal 214 oxides as ideal platforms to explore d-orbital reconstruction in the context of oxide electronics.

No MeSH data available.


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ESR data for Sr2IrO4.(a) Out-of-plane magnetic-field geometries; the inset shows a representative AFR spectrum. (b) In-plane magnetic fields; the inset demonstrates the g-factor anisotropy as function of the tetragonal distortion parameter α (see text). Symbols denote experimental data points—solid lines are theoretical curves using equations (2, 3, 4) and the quantum chemically computed g factors g//=2.31, g⊥=1.76 (see Table 1); dashed lines are calculated assuming isotropic g factors.
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f2: ESR data for Sr2IrO4.(a) Out-of-plane magnetic-field geometries; the inset shows a representative AFR spectrum. (b) In-plane magnetic fields; the inset demonstrates the g-factor anisotropy as function of the tetragonal distortion parameter α (see text). Symbols denote experimental data points—solid lines are theoretical curves using equations (2, 3, 4) and the quantum chemically computed g factors g//=2.31, g⊥=1.76 (see Table 1); dashed lines are calculated assuming isotropic g factors.

Mentions: For a single crystal of Sr2IrO4 we observe antiferromagnetic resonance (AFR) modes in the sub-THz frequency domain26 as displayed in Fig. 2. There are two modes if h//z: a gapless Goldstone mode v//1=0 and a gapped excitation


Orbital reconstruction in nonpolar tetravalent transition-metal oxide layers.

Bogdanov NA, Katukuri VM, Romhányi J, Yushankhai V, Kataev V, Büchner B, van den Brink J, Hozoi L - Nat Commun (2015)

ESR data for Sr2IrO4.(a) Out-of-plane magnetic-field geometries; the inset shows a representative AFR spectrum. (b) In-plane magnetic fields; the inset demonstrates the g-factor anisotropy as function of the tetragonal distortion parameter α (see text). Symbols denote experimental data points—solid lines are theoretical curves using equations (2, 3, 4) and the quantum chemically computed g factors g//=2.31, g⊥=1.76 (see Table 1); dashed lines are calculated assuming isotropic g factors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4491190&req=5

f2: ESR data for Sr2IrO4.(a) Out-of-plane magnetic-field geometries; the inset shows a representative AFR spectrum. (b) In-plane magnetic fields; the inset demonstrates the g-factor anisotropy as function of the tetragonal distortion parameter α (see text). Symbols denote experimental data points—solid lines are theoretical curves using equations (2, 3, 4) and the quantum chemically computed g factors g//=2.31, g⊥=1.76 (see Table 1); dashed lines are calculated assuming isotropic g factors.
Mentions: For a single crystal of Sr2IrO4 we observe antiferromagnetic resonance (AFR) modes in the sub-THz frequency domain26 as displayed in Fig. 2. There are two modes if h//z: a gapless Goldstone mode v//1=0 and a gapped excitation

Bottom Line: We resolve in this regard the d-level structure of layered Sr2IrO4 by electron spin resonance.This implies that the iridium d levels are inverted with respect to their normal ordering.State-of-the-art electronic-structure calculations confirm the level switching in Sr2IrO4, whereas we find them in Ba2IrO4 to be instead normally ordered.

View Article: PubMed Central - PubMed

Affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany.

ABSTRACT
A promising route to tailoring the electronic properties of quantum materials and devices rests on the idea of orbital engineering in multilayered oxide heterostructures. Here we show that the interplay of interlayer charge imbalance and ligand distortions provides a knob for tuning the sequence of electronic levels even in intrinsically stacked oxides. We resolve in this regard the d-level structure of layered Sr2IrO4 by electron spin resonance. While canonical ligand-field theory predicts g//-factors less than 2 for positive tetragonal distortions as present in Sr2IrO4, the experiment indicates g// is greater than 2. This implies that the iridium d levels are inverted with respect to their normal ordering. State-of-the-art electronic-structure calculations confirm the level switching in Sr2IrO4, whereas we find them in Ba2IrO4 to be instead normally ordered. Given the nonpolar character of the metal-oxygen layers, our findings highlight the tetravalent transition-metal 214 oxides as ideal platforms to explore d-orbital reconstruction in the context of oxide electronics.

No MeSH data available.


Related in: MedlinePlus