Magnetic Excitation Spectra of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Sr</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>IrO</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:math>Probed by Resonant Inelastic X-Ray Scattering: Establishing Links to Cuprate Superconductors

Kim, Jungho; Casa, D.; Upton, M. H.; Gög, T.; Kim, Young-June; Mitchell, J. F.; Veenendaal, Michel van; Daghofer, Maria; Brink, Jeroen van den; Khaliullin, Giniyat; Kim, B. J.

doi:10.1103/physrevlett.108.177003

Cited by 478 publications

(634 citation statements)

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“…We first confirm the obtained magnetic excitations as bound states show good agreement with the RIXS experiment. 17 Furthermore, we find two kinds of new excitation modes emerge, which are attributed to the interplay between the SOI and Hund's coupling. One is the gap mode associated with the splitting of the magnetic excitation.…”

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confidence: 81%

“…Notice that, within the analysis of the Heisenberg model on the basis of the localized picture, such result has been reproduced only when the second and third nearest-neighbor exchange terms were included in addition to the first nearest-neighbor exchange term. 17,27 In the present treatment, however, since the hopping term between the nearest neighbor sites alone provides the desired results, the mechanism should be sought for different direction. It might be attributed to the mixing with high energy states.…”

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confidence: 99%

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Interplay between Hund’s Coupling and Spin–Orbit Interaction on Elementary Excitations in Sr₂IrO₄

Igarashi

Nagao

2014

J. Phys. Soc. Jpn.

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We study the elementary excitations in 5d transition metal oxide Sr2IrO4 by calculating the particle-hole Green's function within the random phase approximation on an antiferromagnetic ground state in the two-dimensional multi-orbital Hubbard model. The obtained magnetic excitations of bound states show a characteristic dispersion in consistent with the experiments. In addition, two new types of excitations are found due to the interplay between spin-orbit interaction and Hund's coupling: a magnetic excitation as a bound state, which has energy gap at the Γ point, and an exciton as a resonant mode in the continuum of electron-hole pair creation.Electron correlation effects on transition metals and their compounds have attracted much interest since the discovery of high-T C cuprate superconductors. In the 3d transition metal ions, the spin orbit interaction (SOI) plays a minor role on the electronic structures, since it is usually much smaller than the on-site Coulomb interaction and the crystal field splitting. In the 5d transition metal ions, however, the SOI is one order of magnitude larger than that of the 3d systems while the Coulomb interaction becomes weaker due to the extended nature of the 5d electrons. Accordingly, the interplay between the electron correlation and the SOI is expected to bring about new intriguing phenomena. For this reason, much attention has recently been paid to Ir oxides such as Sr 2 IrO 4 1-8 and Na 2 IrO 3 . [9][10][11][12] In particular, we focus on Sr 2 IrO 4 , which consists of two-dimensional IrO 2 layers showing structural similarity to the parent compound of high-T C cuprate La 2 CuO 4 , and exhibits a canted antiferromagnetic (AFM) order below 230 K. 1-3 The energy of the e g orbitals is estimated about 2 eV higher than that of the t 2g orbitals due to the large crystal field. Five 5d electrons are occupied per Ir atom, and one hole is sitting in the t 2g orbitals. Since the hole states have an effective orbital angular momentum ℓ equal to −1, the lowest-energy states on the localized electron picture are doubly degenerate with the effective total angular momentum j eff = 1 2 under the SOI: 13,14 |φ ± = 1 √ 3 (|yz, ∓σ ± i|zx, ∓σ ± |xy, ±σ ), where yz, zx, and xy designate t 2g orbitals, and spin component σ =↑. By introducing the isospin operators acting on these states, the system is mapped onto the Heisenberg model, from which an insulating AFM phase is derived, consistent with the experiments. 1-3 Furthermore, it has been pointed out that the small anisotropic terms emerge in addition to the isotropic term, when Hund's coupling is taken into account in the second-order process in the strong coupling expansion. 15,16 Recently, resonant inelastic x-ray scattering (RIXS) experiment at the Ir L edge has detected the excitation spectra, 17 whose low energy part follows the dispersion relation similar to the spin wave in the Heisenberg model on a square lattice. A notable point is that the excitation energy at the M point is nearly half of that at the X point, in contrast to t...

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confidence: 81%

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confidence: 99%

Interplay between Hund’s Coupling and Spin–Orbit Interaction on Elementary Excitations in Sr₂IrO₄

Igarashi

Nagao

2014

J. Phys. Soc. Jpn.

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“…The former surprisingly indicates that a system with very strong spin-orbit coupling can mimic a system without it. Experimentally, it has been confirmed that the canted antiferromagnetic structure of Sr 2 IrO 4 derives from a predominantly isotropic nearest-neighbor magnetic exchange coupling [8][9][10] . Thus, Sr 2 IrO 4 becomes the first non-cuprate material to realize a (iso)spin-1/2 Heisenberg antiferromagnet in a quasitwo-dimensional square lattice-a possible platform for high temperature superconductivity [11][12][13][14][15] .…”

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confidence: 99%

Crystal growth and intrinsic magnetic behaviour of Sr₂IrO₄

Sung

Gretarsson

Proepper

et al. 2016

Philosophical Magazine

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We report on the growth of stoichiometric Sr2IrO4 single crystals, which allow us to unveil their intrinsic magnetic properties. The effect of different growth conditions has been investigated for crystals grown by the flux method. We find that the magnetic response depends very sensitively on the details of the growth conditions. We assess the defect concentration based on magnetization, X-ray diffraction, Raman scattering, and optical conductivity measurements. We find that samples with a low concentration of electronically active defects show much reduced in-gap spectral weight in the optical conductivity and a pronounced two-magnon peak in the Raman scattering spectrum. A prolonged exposure at high temperature during the growth leads to higher defect concentration likely due to creation of oxygen vacancies. We further demonstrate a systematic intergrowth of Sr2IrO4 and Sr3Ir2O7 phases by varying the growth temperature. Our results thus emphasize that revealing the intrinsic magnetic properties of Sr2IrO4 and related materials requires a scrupulous control of the crystal growth process.

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“…23 Some papers indicate the ordered moment can be produced via slight canting of the otherwise AF moments. [24][25][26][27] The canting angle (see Fig. 1b) occurs due to the deviation of the Ir-O-Ir angle from 180 • via Dzyaloshinskii-Moriya interaction.…”

Section: Introductionmentioning

confidence: 99%

Noncollinear versus collinear description of the Ir-based one-t2g-hole perovskite-related compounds:SrIrO3andSr2
Lado
¹
,
Pardo
²

2015
Phys. Rev. B
12
5
8
0
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We present an analysis of the electronic structure of perovskite-related iridates, 5d electron compounds where a subtle interplay between spin-orbit coupling, tetragonal distortions and electron correlations determines the electronic structure properties. We suggest via electronic structure calculations that a non-collinear calculation is required to obtain solutions close to the usually quoted j ef f = 1/2 state to describe the t2g hole in the Ir 4+ :d 5 cation, while a collinear calculation yields a different solution, the hole is in a simpler xz/yz complex combination with a smaller Lz/Sz ratio. We describe what the implications of this are in terms of the electronic structure; surprisingly, both solutions barely differ in terms of their band structure, and are similar to the one obtained by a tight binding model involving t2g orbitals with mean field interactions. We also analyze how the electronic structure and magnetism evolve with strain, spin-orbit coupling strength and on-site Coulomb repulsion; we suggest the way the band structure gets modified and draw some comparisons with available experimental observations.

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Magnetic Excitation Spectra ofSr2IrO4Probed by Resonant Inelastic X-Ray Scattering: Establishing Links to Cuprate Superconductors

Cited by 478 publications

References 30 publications

Interplay between Hund’s Coupling and Spin–Orbit Interaction on Elementary Excitations in Sr₂IrO₄

Interplay between Hund’s Coupling and Spin–Orbit Interaction on Elementary Excitations in Sr₂IrO₄

Crystal growth and intrinsic magnetic behaviour of Sr₂IrO₄

Noncollinear versus collinear description of the Ir-based one-t2g-hole perovskite-related compounds:SrIrO3andSr2
Lado
¹
,
Pardo
²

2015
Phys. Rev. B
12
5
8
0
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Magnetic Excitation Spectra ofSr2IrO4Probed by Resonant Inelastic X-Ray Scattering: Establishing Links to Cuprate Superconductors

Cited by 478 publications

References 30 publications

Interplay between Hund’s Coupling and Spin–Orbit Interaction on Elementary Excitations in Sr2IrO4

Interplay between Hund’s Coupling and Spin–Orbit Interaction on Elementary Excitations in Sr2IrO4

Crystal growth and intrinsic magnetic behaviour of Sr2IrO4

Noncollinear versus collinear description of the Ir-based one-t2g-hole perovskite-related compounds:SrIrO3andSr2Lado1, Pardo2 2015Phys. Rev. B12580View full textAdd to dashboardCite

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Interplay between Hund’s Coupling and Spin–Orbit Interaction on Elementary Excitations in Sr₂IrO₄

Interplay between Hund’s Coupling and Spin–Orbit Interaction on Elementary Excitations in Sr₂IrO₄

Crystal growth and intrinsic magnetic behaviour of Sr₂IrO₄

Noncollinear versus collinear description of the Ir-based one-t2g-hole perovskite-related compounds:SrIrO3andSr2
Lado
¹
,
Pardo
²

2015
Phys. Rev. B
12
5
8
0
View full text Add to dashboard Cite