Crystal-Field Splitting and Correlation Effect on the Electronic Structure of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>A</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>IrO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>

Gretarsson, H.; Clancy, J. P.; Liu, X.; Hill, J. P.; Božin, Emil S.; Singh, Yogesh; Manni, Soham; Gegenwart, P.; Kim, Jungho; Said, A. H.; Casa, D.; Gög, T.; Upton, M. H.; Kim, Heung Sik; Yu, Jingkun; Katukuri, Vamshi M.; Hozoi, Liviu; Brink, Jeroen van den; Kim, Yong Baek

doi:10.1103/physrevlett.110.076402

Cited by 257 publications

(320 citation statements)

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“…The spin couplings obtained are reasonable for the 90 • -exchange bonds (as expected [8,11], they are much smaller than in 180 • -bond perovskites [13,14]). The magnitude of Van Vleck term also agrees with our estimate χ 0 ≃ 8 3λ µ 2 B N A ≃ 0.2 × 10 −3 cm 3 /mol for Ir 4+ ion, considering spin-orbit coupling λ ≃ 0.4 eV [13,15,30].…”

supporting

confidence: 79%

“…When λ > (E JT , J), as often realized for Co, Rh, Ir ions in octahedral environment, local moments acquire a large orbital component which may result in a strong departure from spin-only Heisenberg models [8,11]. The direct observation of large spinorbit splitting 3λ/2 ∼ 0.6 − 0.7 eV in insulating iridates Sr 2 IrO 4 [13], Sr 3 Ir 2 O 7 [14], and Na 2 IrO 3 [15] made it certain that λ > (E JT , J). Thus, low-energy physics of Na 2 IrO 3 is governed by interactions among the spin-orbit entangled Kramers doublets of Ir-ions.…”

mentioning

confidence: 99%

“…This approximation is valid as long as ∆ is much smaller than spin-orbit coupling λ ≃ 0.4 eV [13,15,30] and seems to be justified, since the recent ab-initio calculations [20] suggest that ∆ ≃ 75 meV only [31].…”

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confidence: 99%

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Zigzag Magnetic Order in the Iridium OxideNa2IrO3

2013

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We explore the phase diagram of spin-orbit Mott insulators on a honeycomb lattice, within the Kitaev-Heisenberg model extended to its full parameter space. Zigzag-type magnetic order is found to occupy a large part of the phase diagram of the model, and its physical origin is explained as due to interorbital t2g − eg hopping. Magnetic susceptibility and spin wave spectra are calculated and compared to the experimental data, obtaining thereby the spin coupling constants in Na2IrO3 and Li2IrO3.

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confidence: 79%

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Zigzag Magnetic Order in the Iridium OxideNa2IrO3

2013

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“…In addition to the QP, a small peak with the dispersion minimum at the G point at EE0.37 eV is observed. A similar peak has been observed in a related material Na 2 IrO 3 and attributed to a bound state at the edge of the particle-hole continuum 29 .…”

Section: Resultssupporting

confidence: 49%

“…While such a sharp peak is not uncommon in RIXS spectra of iridates 29 , it is certainly much narrower than that of the sharpest peak (B200 meV) in the hole spectral function measured by ARPES for the same material 13,30 . The peak width is also much smaller than its total bandwidth (E112 meV), which establishes the exciton as a propagating mode in a solid, or a QP.…”

Section: Resultsmentioning

confidence: 93%

Excitonic quasiparticles in a spin–orbit Mott insulator

et al. 2014

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In condensed matter systems, out of a large number of interacting degrees of freedom emerge weakly coupled quasiparticles (QPs), in terms of which most physical properties are described. The lack of identification of such QPs is a major barrier for understanding myriad exotic properties of correlated electrons, such as unconventional superconductivity and non-Fermi liquid behaviours. Here we report the observation of a composite particle in a quasi-two-dimensional spin-1/2 antiferromagnet Sr 2 IrO 4 -an exciton dressed with magnons-that propagates with the canonical characteristics of a QP: a finite QP residue and a lifetime longer than the hopping time scale. The dynamics of this charge-neutral excitation mirrors the fundamental process of the analogous one-hole propagation in the background of spins-1/2, and reveals the same intrinsic dynamics that is obscured for a single, charged-hole doped into two-dimensional cuprates.

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Magnetic Properties from the Perspectives of Electronic Hamiltonian

Whangbo

Xiang

2017

Handbook of Solid State Chemistry

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In this chapter, we review the quantitative and qualitative aspects of describing the properties of magnetic solids on the basis of electronic Hamiltonian that describes the energy states of a magnetic system using both orbital and spin degrees of freedom. To quantitatively discuss a magnetic property of a given magnetic system, one needs to generate the spectrum of its energy states and subsequently average the properties of these states with each state weighted by its Boltzmann distribution factor. Currently, this is an impossible task to achieve on the basis of an electronic Hamiltonian, so it is necessary to resort to a simple model Hamiltonian, that is, a spin Hamiltonian that describes the energy states of a magnetic system using only the spin degree of freedom. We show that a spin Hamiltonian approach becomes consistent with an electronic Hamiltonian approach if the spin lattice and its associated spin exchange parameters, to be used for the spin Hamiltonian, are determined by the energy‐mapping analysis based onDFTcalculations. The preferred spin orientation (i.e., the magnetic anisotropy) of a magnetic ion is not predicted by a spin Hamiltonian because it does not include the orbital degree of freedom explicitly. In contrast, the magnetic anisotropy is readily predicted by electronic structure theories employing both orbital and spin degrees of freedom, if one takes into consideration the spin–orbit coupling (SOC), , of a magnetic ion where and are, respectively, the spin and orbital operators and λ theSOCconstant. It was shown that the preferred spin orientation of a magnetic ion can be predicted and understood in terms of theHOMO–LUMOinteractions of the magnetic ion by takingSOC, , as perturbation. A spin Hamiltonian gives rise to the spin‐half misconception, namely, the blind belief that spin‐half magnetic ions do not possess magnetic anisotropy that arise fromSOC. This misconception contradicts not only experimental observations on spin‐half ions but also theoretical results based onDFTcalculations and perturbation theory analyses based on an electronic Hamiltonian. This misconception is a direct consequence from the limitedness of a spin Hamiltonian that it lacks the orbital degree of freedom. We show that the magnetic properties of 5dion oxides are better explained by theLS‐coupling than by thejj‐coupling scheme ofSOC, and the spin‐orbital entanglement of 5dions is not as strong as has been assumed.

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Crystal-Field Splitting and Correlation Effect on the Electronic Structure ofA2IrO3

Cited by 257 publications

References 48 publications

Zigzag Magnetic Order in the Iridium OxideNa2IrO3

Zigzag Magnetic Order in the Iridium OxideNa2IrO3

Excitonic quasiparticles in a spin–orbit Mott insulator

Magnetic Properties from the Perspectives of Electronic Hamiltonian

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