@article{d4c7b3f71b494e29b02ae393d2679df3,
title = "High-energy spin and charge excitations in electron-doped copper oxide superconductors",
abstract = "The evolution of electronic (spin and charge) excitations upon carrier doping is an extremely important issue in superconducting layered cuprates and the knowledge of its asymmetry between electron- and hole-dopings is still fragmentary. Here we combine X-ray and neutron inelastic scattering measurements to track the doping dependence of both spin and charge excitations in electron-doped materials. Copper L3 resonant inelastic X-ray scattering spectra show that magnetic excitations shift to higher energy upon doping. Their dispersion becomes steeper near the magnetic zone centre and they deeply mix with charge excitations, indicating that electrons acquire a highly itinerant character in the doped metallic state. Moreover, above the magnetic excitations, an additional dispersing feature is observed near the γ-point, and we ascribe it to particle-hole charge excitations. These properties are in stark contrast with the more localized spin excitations (paramagnons) recently observed in hole-doped compounds even at high doping levels.",
author = "K. Ishii and M. Fujita and T. Sasaki and M. Minola and G. Dellea and C. Mazzoli and K. Kummer and G. Ghiringhelli and L. Braicovich and T. Tohyama and K. Tsutsumi and K. Sato and R. Kajimoto and K. Ikeuchi and K. Yamada and M. Yoshida and M. Kurooka and J. Mizuki",
note = "Funding Information: We acknowledge K. Tsutsui, E. Kaneshita, S. Wakimoto, and H. Kimura for invaluable discussion. We also thank H. Kimura for sample preparation and N.B. Brookes for the support at the beam line ID08 of the European Synchrotron Radiation Facility (ESRF). The Cu L3 RIXS experiments were performed at the beam line ID08 of the ESRF using the AXES spectrometer and we acknowledge the ESRF for provision of synchrotron radiation facilities. The INS experiments at J-PARC were carried out under Project No. 2012P0201. The Cu K-edge RIXS experiments at SPring-8 were performed with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposals No. 2012B3502). This work is financially supported by JSPS KAKENHI Grant Number 25400333, 23340093 and 22340097. G.D., G.G. and L.B. are supported by the Italian Ministry of Research (MIUR) through the PIK-POLARIX project. T.T. is supported by Strategic Programs for Innovative Research (SPIRE), the Computational Materials Science Initiative (CMSI) from MEXT, and K.Is., M.F. and T.T. acknowledge YIPQS Molecule-type workshop at YITP. This work was partly performed under the InterUniversity Cooperative Research Program of the Institute for Materials Research, Tohoku University (Proposal No. 12K0092).",
year = "2014",
month = apr,
day = "25",
doi = "10.1038/ncomms4714",
language = "English",
volume = "5",
journal = "Nature Communications",
issn = "2041-1723",
publisher = "Nature Publishing Group",
}