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Crystalline and magnetic structure of Ba 2 CuO 3 + δ investigated by x-ray absorption spectroscopy and resonant inelastic x-ray scattering

DOI: 10.1016/j.physc.2020.1353810 DOI Help

Authors: Roberto Fumagalli (Politecnico di Milano; Max-Planck-Institut für Festkörperforschung) , Abhishek Nag (Diamond Light Source; Max-Planck-Institut für Festkörperforschung) , Stefano Agrestini (Max Planck Institute for Chemical Physics of Solids; Max-Planck-Institut für Festkörperforschung) , Mirian Garcia-fernandez (Diamond Light Source; Max-Planck-Institut für Festkörperforschun) , Andrew C. Walters (Diamond Light Source) , Davide Betto (ESRF – The European Synchrotron; Max-Planck-Institut für Festkörperforschung) , Nicholas B. Brookes (ESRF – The European Synchrotron; Max-Planck-Institut für Festkörperforschung) , Lucio Braicovich (Politecnico di Milano; ESRF – The European Synchrotron; Max-Planck-Institut für Festkörperforschung) , Kejin Zhou (Diamond Light Source; Max-Planck-Institut für Festkörperforschung) , Giacomo Ghiringhelli (Politecnico di Milano; CNR-SPIN, Politecnico di Milano; Max-Planck-Institut für Festkörperforschung) , Marco Moretti Sala (Politecnico di Milano; Max-Planck-Institut für Festkörperforschung)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physica C: Superconductivity And Its Applications

State: Published (Approved)
Published: December 2020
Diamond Proposal Number(s): 23413

Abstract: Motivated by the recent synthesis of Ba CuO (BCO), a high temperature superconducting cuprate with putative ground state symmetry, we investigated its electronic structure by means of Cu x-ray absorption (XAS) and resonant inelastic x-ray scattering (RIXS) at the Cu edge on a polycrystalline sample. We show that the XAS profile of BCO is characterised by two peaks associated to inequivalent Cu sites, and that its RIXS response features a single, sharp peak associated to crystal-field excitations. We argue that these observations are only partially compatible with the previously proposed crystal structure of BCO. Based on our spectroscopic results and on previously published powder diffraction measurements, we propose a crystalline structure characterized by two inequivalent Cu sites located at alternated planes along the axis: nominally trivalent Cu(1) belonging to very short Cu-O chains, and divalent Cu(2) in the oxygen deficient CuO planes. We also analyze the low-energy region of the RIXS spectra to estimate the magnitude of the magnetic interactions in BCO and find that in-plane nearest neighbor superexchange exceeds 120 meV, similarly to that of other layered cuprates. Although these results do not support the pure ground state scenario, they hint at a significant departure from the common quasi-2D electronic structure of superconducting cuprates of pure symmetry.

Journal Keywords: Superconductivity; XAS; RIXS; cuprates

Subject Areas: Materials, Physics


Instruments: I21-Resonant Inelastic X-ray Scattering (RIXS)