Search Results

You searched for all publications:

with publication states 'Published (Approved)'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

6 items found (0 items not approved), displaying all items.1

Instruments / Technical Area	Publication Details	Published
I21-Resonant Inelastic X-ray Scattering (RIXS)	Strongly correlated charge density wave in La2−xSrxCuO4 evidenced by doping-dependent phonon anomaly J. Q. Lin , H. Miao , D. G. Mazzone , G. D. Gu , A. Nag , A. C. Walters , M. Garcia-fernandez , A. Barbour , J. Pelliciari , I. Jarrige , M. Oda , K. Kurosawa , N. Momono , K. Zhou , V. Bisogni , X. Liu , M. P. M. Dean Physical Review Letters 124 DOI: 10.1103/PhysRevLett.124.207005 Diamond Proposal Number(s): [22261] Show Abstract ▼ Abstract: The discovery of charge-density-wave-related effects in the resonant inelastic x-ray scattering spectra of cuprates holds the tantalizing promise of clarifying the interactions that stabilize the electronic order. Here, we report a comprehensive resonant inelastic x-ray scattering study of La 2 − x Sr x CuO 4 finding that charge-density wave effects persist up to a remarkably high doping level of x = 0.21 before disappearing at x = 0.25 . The inelastic excitation spectra remain essentially unchanged with doping despite crossing a topological transition in the Fermi surface. This indicates that the spectra contain little or no direct coupling to electronic excitations near the Fermi surface, rather they are dominated by the resonant cross section for phonons and charge-density-wave-induced phonon softening. We interpret our results in terms of a charge-density wave that is generated by strong correlations and a phonon response that is driven by the charge-density-wave-induced modification of the lattice.	May 2020
I21-Resonant Inelastic X-ray Scattering (RIXS)	Many-body physics of single and double spin-flip excitations in NiO A. Nag , H. C. Robarts , F. Wenzel , J. Li , H. Elnaggar , R.-p. Wang , A. Walters , M. Garcia-fernandez , F. M. F. De Groot , M. W. Haverkort , K. Zhou Physical Review Letters 124 DOI: 10.1103/PhysRevLett.124.067202 Open Access Show Abstract ▼ Abstract: Understanding many-body physics of elementary excitations has advanced our control over material properties. Here, we study spin-flip excitations in NiO using Ni L3-edge resonant inelastic x-ray scattering (RIXS) and present a strikingly different resonant energy behavior between single and double spin-flip excitations. Comparing our results with single-site full-multiplet ligand field theory calculations we find that the spectral weight of the double-magnon excitations originates primarily from the double spin-flip transition of the quadrupolar RIXS process within a single magnetic site. Quadrupolar spin-flip processes are among the least studied excitations, despite being important for multiferroic or spin-nematic materials due to their difficult detection. We identify intermediate state multiplets and intra-atomic core-valence exchange interactions as the key many-body factors determining the fate of such excitations. RIXS resonant energy dependence can act as a convincing proof of existence of nondipolar higher-ranked magnetic orders in systems for which, only theoretical predictions are available.	Feb 2020
I21-Resonant Inelastic X-ray Scattering (RIXS)	Electronic structure of the parent compound of superconducting infinite-layer nickelates M. Hepting , D. Li , C. J. Jia , H. Lu , E. Paris , Y. Tseng , X. Feng , M. Osada , E. Been , Y. Hikita , Y.-d. Chuang , Z. Hussain , K. J. Zhou , A. Nag , M. Garcia-fernandez , M. Rossi , H. Y. Huang , D. J. Huang , Z. X. Shen , T. Schmitt , H. Y. Hwang , B. Moritz , J. Zaanen , T. P. Devereaux , W. S. Lee Nature Materials 59 DOI: 10.1038/s41563-019-0585-z Diamond Proposal Number(s): [22009] Show Abstract ▼ Abstract: The search continues for nickel oxide-based materials with electronic properties similar to cuprate high-temperature superconductors. The recent discovery of superconductivity in the doped infinite-layer nickelate NdNiO2 has strengthened these efforts. Here, we use X-ray spectroscopy and density functional theory to show that the electronic structure of LaNiO2 and NdNiO2, while similar to the cuprates, includes significant distinctions. Unlike cuprates, the rare-earth spacer layer in the infinite-layer nickelate supports a weakly interacting three-dimensional 5d metallic state, which hybridizes with a quasi-two-dimensional, strongly correlated state with 3 d x 2 − y 2 3dx2−y2 symmetry in the NiO2 layers. Thus, the infinite-layer nickelate can be regarded as a sibling of the rare-earth intermetallics, which are well known for heavy fermion behaviour, where the NiO2 correlated layers play an analogous role to the 4f states in rare-earth heavy fermion compounds. This Kondo- or Anderson-lattice-like ‘oxide-intermetallic’ replaces the Mott insulator as the reference state from which superconductivity emerges upon doping.	Jan 2020
I21-Resonant Inelastic X-ray Scattering (RIXS)	Superstructure control of first-cycle voltage hysteresis in O-redox cathodes Robert A. House , Urmimala Maitra , Miguel A. Pérez-osorio , Juan G. Lozano , Liyu Jin , James W. Somerville , Laurent C. Duda , Abhishek Nag , Andrew Walters , Kejin Zhou , Matthew R. Roberts , Peter G. Bruce Nature DOI: 10.1038/s41586-019-1854-3 Show Abstract ▼ Abstract: Alkali-rich transition metal oxide intercalation cathodes can increase the energy density of Li and Na-ion batteries by storing charge on the oxide and transition metal (TM) ions1–10. The high voltage associated with oxidation of O2- on the first charge is not recovered on discharge, resulting in significantly reduced energy density11. Displacement of TM ions from the TM to alkali metal layers has been proposed to explain the first cycle voltage loss9,12–16. By comparing two closely related intercalation cathodes, Na0.75[Li0.25Mn0.75]O2 and Na0.6[Li0.2Mn0.8]O2, we show that the first cycle voltage hysteresis is determined by the superstructure, specifically the local ordering of Li/TM ions in the TM layers. The honeycomb superstructure of Na0.75[Li0.25Mn0.75]O2, present in almost all O-redox compounds, is lost on charging, driven, in part, by formation of molecular O2 inside the solid. The O2 molecules are cleaved on discharge reforming O2-, but the Mn ions have migrated in the plane changing the coordination around O2- significantly lowering the voltage on discharge (hysteresis). The ribbon superstructure in Na0.6[Li0.2Mn0.8]O2 inhibits Mn disorder and hence O2 formation, suppressing hysteresis and promoting stable electron holes on O2- which are revealed by XAS. The results show that voltage hysteresis can be avoided in O-redox cathodes by forming materials with a superstructure (cation ordering) in the TM layers that suppresses TM migration.	Dec 2019
I21-Resonant Inelastic X-ray Scattering (RIXS)	Anisotropic damping and wave vector dependent susceptibility of the spin fluctuations in La 2 − x Sr x CuO 4 studied by resonant inelastic x-ray scattering H. C. Robarts , M. Barthelemy , K. Kummer , Mirian Garcia-fernandez , J. Li , A. Nag , A. C. Walters , K. Zhou , S. M. Hayden Physical Review B 100 DOI: 10.1103/PhysRevB.100.214510 Diamond Proposal Number(s): [18469, 18512] Show Abstract ▼ Abstract: We report high-resolution resonant inelastic x-ray scattering (RIXS) measurements of the collective spin fluctuations in three compositions of the superconducting cuprate system La 2 − x Sr x CuO 4 . We have mapped out the excitations throughout much of the two-dimensional ( h , k ) Brillouin zone. The spin fluctuations in La 2 − x Sr x CuO 4 are found to be fairly well described by a damped harmonic oscillator model, thus our data allows us to determine the full wave vector dependence of the damping parameter. This parameter increases with doping and is largest along the ( h , h ) line, where it is peaked near ( 0.2 , 0.2 ) . We have used a new procedure to determine the absolute wave vector dependent susceptibility for the doped compositions La 2 − x Sr x CuO 4 ( x = 0.12 , 0.16 ) by normalizing our data to La 2 CuO 4 measurements made with inelastic neutron scattering (INS). We find that the evolution with doping of the intensity of high-energy excitations measured by RIXS and INS is consistent. For the doped compositions, the wave vector dependent susceptibility is much larger at ( 1 4 , 1 4 ) than at ( 1 2 , 0 ) . It increases rapidly along the ( h , h ) line towards the antiferromagnetic wave vector of the parent compound ( 1 2 , 1 2 ) . Thus, the strongest magnetic excitations, and those predicted to favor superconductive pairing, occur towards the ( 1 2 , 1 2 ) position as observed by INS.	Dec 2019
I21-Resonant Inelastic X-ray Scattering (RIXS)	High-resolution resonant inelastic x-ray scattering study of the electron-phonon coupling in honeycomb α − Li 2IrO3 J. G. Vale , C. D. Dashwood , E. Paris , L. S. I. Veiga , Mirian Garcia-fernandez , A. Nag , A. Walters , K. Zhou , I.-m. Pietsch , Anton Jesche , P. Gegenwart , R. Coldea , T. Schmitt , D. F. Mcmorrow Physical Review B 100 DOI: 10.1103/PhysRevB.100.224303 Diamond Proposal Number(s): [20569] Show Abstract ▼ Abstract: The excitations in honeycomb α − Li 2 IrO 3 have been investigated with high-resolution resonant inelastic x-ray scattering (RIXS) at the O K edge. The low-energy response is dominated by a fully resolved ladder of excitations, which we interpret as being due to multiphonon processes in the presence of strong electron-phonon coupling (EPC). At higher energies, the orbital excitations are shown to be dressed by phonons. The high quality of the data permits a quantitative test of the analytical model for the RIXS cross section, which has been proposed to describe EPC in transition-metal oxides (TMOs). We find that the magnitude of the EPC is comparable to that found for a range of 3 d TMOs. This indicates that EPC may be of equal importance in determining the phenomenology displayed by corresponding 5 d -based systems.	Dec 2019

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User