Momentum-resolved resonant inelastic soft X-ray scattering (qRIXS) endstation at the ALS

Chuang, Yi‐De; Feng, Xuefei; Cruz, Alejandro G.; Hanzel, K.; Brown, Andrew F.; Spucces, Adrian; Frañó, Alex; Lee, Cynthia Wei-Sheng; Kim, Jaemyung; Chen, Yu-Jen; Smith, Brian V.; Pepper, John; Shao, Yu; Huang, Shih Wen; Wray, L. Andrew; Gullikson, Eric M.; Shen, Z.‐X.; Devereaux, T. P.; Tremsin, Anton S.; Yang, Wanli; Guo, Jinghua; Duarte, Robert; Hussain, Zahid

doi:10.1016/j.elspec.2019.146897

Cited by 9 publications

(9 citation statements)

References 35 publications

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“…O K-edge XAS measurements were performed at Beamline 8.0.1 at the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory; Beamline 20A at the Taiwan Light Source, National Synchrotron Radiational Research Center (NSRRC); and Beamline 02B at the Shanghai Synchrotron Radiation Facility (SSRF) [30]. The results from these facilities are consistent with each other and in this paper, we only show the data from the ALS.…”

Section: Methodssupporting

confidence: 68%

Enhanced orbital anisotropy through the proximity to a SrTiO3 layer in the perovskite iridate superlattices

et al. 2021

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We have used angle-dependent soft x-ray absorption spectroscopy (XAS) at the O K edge and first-principles calculations to investigate the electronic structures of iridate-based superlattices (SrIrO 3 ) m /(SrTiO 3 )(m = 1, 2, 3, and Ý). We focus on the pre-edge Ir 5dt 2g -O 2p orbital hybridization feature in the XAS spectra. By varying the measurement geometry relative to the incident photon polarization, we are able to extract the dichroic contrast and observe the systematic increase in the anisotropy of Ir 5d orbitals as m decreases. First-principles calculations elucidate the orbital anisotropy coming mainly from the enhanced out-of-plane compression of IrO 6 octahedra in the SrIrO 3 layers that are adjacent to the inserted SrTiO 3 layers. As m decreases, the increased volume fraction of these interfacial SrIrO 3 layers and their contact with the SrTiO 3 layers within the (SrIrO 3 ) m /(SrTiO 3 ) supercell lead to enhanced orbital anisotropy. Furthermore, the tilt and rotation of IrO 6 octahedra are shown to be essential to understand the subtle orbital anisotropy in these superlattices, and constraining these degrees of freedom will give an incorrect trend. Our results demonstrate that the structural constraint from the inserted SrTiO 3 layers, in addition to other electronic means such as polar interface and charge transfer, can serve as a knob to control the orbital degree of freedom in these iridate-based superlattices.

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Section: Methodssupporting

confidence: 68%

Enhanced orbital anisotropy through the proximity to a SrTiO3 layer in the perovskite iridate superlattices

et al. 2021

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“…To provide insights for the emergent electronic reconstruction due to Mott-Hubbard localization [21] as well as the emergence of upper Hubbard bands [22] in the monoclinic and rhombohedral structural phases of paramagnetic CrI 3 , we use x-ray absorption spectroscopy (XAS). The total fluorescence yield (TFY) mode of XAS spectra were recorded using the qRIXS end station at Beamline 8.0.1 at the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory [35]. Commercial CrI 3 samples from HQ graphene were used in the measurement.…”

Section: Resultsmentioning

confidence: 99%

Mott localization in the van der Waals crystal CrI3 : A GGA+DMFT study

et al. 2020

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Using the generalized gradient approximation plus dynamical mean-field theory (GGA+DMFT) we confirm the importance of multi-orbital dynamical correlations in determining the paramagnetic insulating state of CrI 3 . While the ferromagnetic phase reveals weak electronic correlation effects due to strong spin-orbital polarization, the Mott insulating state of paramagnetic CrI 3 crystal is shown to be driven by the interplay between orbital-dependent one-electron lineshape and multi-orbital electronic interactions. To probe the paramagnetic Mott insulating state we performed x-ray absorption spectroscopy (XAS) measurements for the two structural phases of CrI 3 . Our study is relevant to understanding the orbital-selective electronic structure reconstruction of Mott insulators and should be applicable to other van der Waals bonded materials from bulk to the ultrathin limit.

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“…The Xray absorption (XAS) and RIXS experiments were carried out on the ex-situ cleaved, commercial HOPG at both iRIXS and qRIXS endstations at beamline 8.0.1 at the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory (LBNL). [31][32][33][34] During the measurements, the π-polarization was used with Γ-K direction oriented in the horizontal scattering plane, see Figure 3(a) for the experimental geometry. For more details about the experiments, see Supplementary Information (SI).…”

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confidence: 99%

Disparate Exciton-Phonon Couplings for Zone-Center and Boundary Phonons in Solid-State Graphite

et al. 2020

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The exciton-phonon coupling in highly oriented pyrolytic graphite is studied using resonant inelastic X-ray scattering (RIXS) spectroscopy. With ~ 70 meV energy resolution, multiple low energy excitations associated with coupling to phonons can be clearly resolved in RIXS spectra. Using resonance dependence and the closed form for RIXS cross-section without considering the intermediate state mixing of phonon modes, the dimensionless coupling constant g is determined to be 5 and 0.4, corresponding to the coupling strength of 0.42 eV +/-40 meV and 0.21 eV +/-30 meV, for zone center and boundary phonons respectively. The reduced g value for zone-boundary phonon may be related to its double resonance nature.

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Momentum-resolved resonant inelastic soft X-ray scattering (qRIXS) endstation at the ALS

Cited by 9 publications

References 35 publications

Enhanced orbital anisotropy through the proximity to a SrTiO3 layer in the perovskite iridate superlattices

Enhanced orbital anisotropy through the proximity to a SrTiO3 layer in the perovskite iridate superlattices

Mott localization in the van der Waals crystal CrI3 : A GGA+DMFT study

Disparate Exciton-Phonon Couplings for Zone-Center and Boundary Phonons in Solid-State Graphite

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