by Fumagalli, Roberto, Nag, Abhishek, Agrestini, Stefano, Garcia-Fernandez, Mirian, Walters, Andrew C., Betto, Davide, Brookes, Nicholas B., Braicovich, Lucio, Zhou, Ke-Jin, Ghiringhelli, Giacomo and Moretti Sala, Marco
Abstract:
Motivated by the recent synthesis of Ba2CuO3+δ (BCO), a high temperature superconducting cuprate with putative d3z ground state symmetry, we investigated its electronic structure by means of Cu L3 x-ray absorption (XAS) and resonant inelastic x-ray scattering (RIXS) at the Cu L3 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 c axis: nominally trivalent Cu(1) belonging to very short Cu-O chains, and divalent Cu(2) in the oxygen deficient CuO1.5 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 d3z ground state scenario, they hint at a significant departure from the common quasi-2D electronic structure of superconducting cuprates of pure dx symmetry. © 2020
Reference:
Crystalline and magnetic structure of Ba2CuO3+δ investigated by x-ray absorption spectroscopy and resonant inelastic x-ray scattering (Fumagalli, Roberto, Nag, Abhishek, Agrestini, Stefano, Garcia-Fernandez, Mirian, Walters, Andrew C., Betto, Davide, Brookes, Nicholas B., Braicovich, Lucio, Zhou, Ke-Jin, Ghiringhelli, Giacomo and Moretti Sala, Marco), In Physica C: Superconductivity and its Applications, volume 581, 2021.
Bibtex Entry:
@ARTICLE{Fumagalli2021,
author = {Fumagalli, Roberto and Nag, Abhishek and Agrestini, Stefano and Garcia-Fernandez, Mirian and Walters, Andrew C. and Betto, Davide and Brookes, Nicholas B. and Braicovich, Lucio and Zhou, Ke-Jin and Ghiringhelli, Giacomo and Moretti Sala, Marco},
title = {Crystalline and magnetic structure of Ba2CuO3+δ investigated by x-ray absorption spectroscopy and resonant inelastic x-ray scattering},
year = {2021},
journal = {Physica C: Superconductivity and its Applications},
volume = {581},
doi = {10.1016/j.physc.2020.1353810},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85099701000&doi=10.1016%2fj.physc.2020.1353810&partnerID=40&md5=357e62ea98a1653bc40b3e7e383da545},
abstract = {Motivated by the recent synthesis of Ba2CuO3+δ (BCO), a high temperature superconducting cuprate with putative d3z ground state symmetry, we investigated its electronic structure by means of Cu L3 x-ray absorption (XAS) and resonant inelastic x-ray scattering (RIXS) at the Cu L3 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 c axis: nominally trivalent Cu(1) belonging to very short Cu-O chains, and divalent Cu(2) in the oxygen deficient CuO1.5 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 d3z ground state scenario, they hint at a significant departure from the common quasi-2D electronic structure of superconducting cuprates of pure dx symmetry. © 2020},
author_keywords = {cuprates; RIXS; Superconductivity; XAS},
correspondence_address = {M. Moretti Sala; Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Italy; email: marco.moretti@polimi.it},
type = {Article},
publication_stage = {Final},
source = {Scopus},
note = {All Open Access, Green Open Access}
}
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