Using RIXS to Uncover Elementary Charge and Spin Excitations

Jia, Chunjing; Wohlfeld, Krzysztof; Wang, Yao; Moritz, Brian; Devereaux, T. P.

doi:10.1103/physrevx.6.021020

Cited by 86 publications

(133 citation statements)

References 60 publications

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“…One can show that such a resonance approximation for the 2p propagator (which neglects the contributions from other edges) works well for RIXS at either the Cu L 2 or L 3 edge [31,32]. As shown in these references and by a number of other recent works, the effect of the core hole does make qualitative changes to the overall resonance profile of RIXS.…”

Section: Expressions For Phonon Contributions To Rixsmentioning

confidence: 63%

Directly Characterizing the Relative Strength and Momentum Dependence of Electron-Phonon Coupling Using Resonant Inelastic X-Ray Scattering

Devereaux¹,

Shvaika²,

Wu³

et al. 2016

Phys. Rev. X

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The coupling between lattice and charge degrees of freedom in condensed matter materials is ubiquitous and can often result in interesting properties and ordered phases, including conventional superconductivity, charge-density wave order, and metal-insulator transitions. Angle-resolved photoemission spectroscopy and both neutron and nonresonant x-ray scattering serve as effective probes for determining the behavior of appropriate, individual degrees of freedom-the electronic structure and lattice excitation, or phonon dispersion, respectively. However, each provides less direct information about the mutual coupling between the degrees of freedom, usually through self-energy effects, which tend to renormalize and broaden spectral features precisely where the coupling is strong, impacting one's ability to quantitatively characterize the coupling. Here, we demonstrate that resonant inelastic x-ray scattering, or RIXS, can be an effective tool to directly determine the relative strength and momentum dependence of the electron-phonon coupling in condensed matter systems. Using a diagrammatic approach for an eight-band model of copper oxides, we study the contributions from the lowest-order diagrams to the full RIXS intensity for a realistic scattering geometry, accounting for matrix element effects in the scattering cross section, as well as the momentum dependence of the electron-phonon coupling vertex. A detailed examination of these maps offers a unique perspective into the characteristics of electron-phonon coupling, which complements both neutron and nonresonant x-ray scattering, as well as Raman and infrared conductivity.

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Section: Expressions For Phonon Contributions To Rixsmentioning

confidence: 63%

Directly Characterizing the Relative Strength and Momentum Dependence of Electron-Phonon Coupling Using Resonant Inelastic X-Ray Scattering

Devereaux¹,

Shvaika²,

Wu³

et al. 2016

Phys. Rev. X

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“…As we did in prior works 23,25,30,31 and following Fig. 1, we might assume that both ground-state and excitedstate energies are parabolic with respect to some parameter driving a one-dimensional path in the set of configurations.…”

Section: Introductionmentioning

confidence: 95%

“…These materials are widely studied because of their commercial use in white LEDs and as scintillators. 20,25,26 The unique 4f 1 electron configuration and the fast parity-allowed electric-dipole 4f-5d transition of the Ce 3+ ions allows for the manufacturing of luminescent centers in optical materials with broadband character. 21,[27][28][29][30] To design a commercial product with better performance, full understanding of the physical mechanisms governing luminescence efficiencies is required.…”

Section: Introductionmentioning

confidence: 99%

Beyond the one-dimensional configuration coordinate model of photoluminescence

et al. 2019

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The one-dimensional configuration coordinate model (1D-CCM) is widely used for the analysis of photoluminescence in molecules and doped solids, and relies on a linear combination of the equilibrium nuclear configurations of ground and excited states. It delivers an estimation of the energy barrier at which ground and excited state curves cross, semi-classically linked to non-radiative transition rate and thermal quenching. To assess its predictive power for the latter properties, we propose a new optimized configuration path (OCP) method in which the ground-state and excitedstate forces are mixed instead of their configurations. We also define another one-parameter model thanks a double energy parabola hypothesis (DEPH). We compare the OCP method and the DEPH reference with the 1D-CCM for three paradigmatic 4f-5d phosphors Y3Al5O12:Ce, Lu2SiO5:Ce, and YAlO3:Ce. We find that the OCP and DEPH methods yield similar results with geometries that have significantly lower ground-state energies than the 1D-CCM for the same 4f-5d energy difference. However, the OCP method suffers from the appearance of multiple local minima, rendering the clear determination of the optimal geometry very difficult in practice. Still the OCP method allows one to quantify the deviations from the 1D-CCM, therefore increasing confidence in the lower bound obtained from the DEPH for the 4f-5d crossing barrier, and its comparison with the energy of the auto-ionization thermal quenching mechanism. We expect the OCP approach to be applicable to other luminescent materials or molecules.

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“…[37], a full SB theory contains four Boson fields instead of only one in our case. Also, it is possible that the RIXS measurements only qualitatively agree with the spin dynamic structure factor, as mentioned by a very recent theoretical work [38]. Furthermore, the core effect and detailed spin-flipping processes have to be included in the full treatment of the Kramers-Heisenberg theory (as was done in Ref.…”

Section: Discussionmentioning

confidence: 99%

Signatures of strong correlation effects in resonant inelastic x-ray scattering studies on cuprates

Lin

Lee

2016

Phys. Rev. B

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Recently, spin excitations in doped cuprates have been measured using resonant inelastic x-ray scattering. The paramagnon dispersions show the large hardening effect in the electron-doped systems and seemingly doping independence in the hole-doped systems, with the energy scales comparable to that of the antiferromagnetic (AFM) magnons. This anomalous hardening effect and the lack of softening were partially explained by using the strong-coupling t − J model but with a three-site term [Nat. Commun. 5, 3314 (2014)], although the hardening effect is already present even without the latter. By considering the t − t − t − J model and using the slave-boson mean-field theory, we obtain, via the spin-spin susceptibility, the spin excitations in qualitative agreement with the experiments. The doping-dependent bandwidth due to the strong correlation physics is the origin of the hardening effect. We also show that dispersions in the AFM regime, different from those in the paramagnetic (PM) regime, hardly vary with dopant density. These excitations are mainly collective in nature instead of particle-hole-like. We further discuss the interplay and different contributions of these two kinds of excitations in the PM phase and show that the dominance of the collective excitation increases with decreasing dopant concentrations.

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Using RIXS to Uncover Elementary Charge and Spin Excitations

Cited by 86 publications

References 60 publications

Directly Characterizing the Relative Strength and Momentum Dependence of Electron-Phonon Coupling Using Resonant Inelastic X-Ray Scattering

Directly Characterizing the Relative Strength and Momentum Dependence of Electron-Phonon Coupling Using Resonant Inelastic X-Ray Scattering

Beyond the one-dimensional configuration coordinate model of photoluminescence

Signatures of strong correlation effects in resonant inelastic x-ray scattering studies on cuprates

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