Neutron spectroscopy in ErBa2Cu3Ox (6 ⩽ × ⩽ 7) and Pr2 − xCexCuO4 − δ (0 ⩽ × ⩽ 0.2): Charge transfer, cluster formation and percolative superconductivity

Allenspach, P.; Fürrer, A.; Fauth, François; Guillaume, Marcel; Henggeler, W.; Mesot, J.; Rosenkranz, S.

doi:10.1016/0921-4526(95)00067-j

Cited by 4 publications

(2 citation statements)

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“…The first one related to the refinement of the pair density function, 26 obtained from neutron powder diffraction data, shows that the CuO 2 planes are quite inhomogeneous with a distribution of undistorted and distorted domains whose origin is not explained by steric arguments ͑i.e., the distortion does not take place in the close proximity of the dopant ions͒. The second scenario reported by Allenspach et al 27 invokes static phase separation into local regions of doped and antiferromagnetic character, respectively. In order to better understand the influence of cerium, we have measured the temperature evolution of the Pr 2Ϫx Ce x CuO 4 single crystal microwave conduc-FIG.…”

Section: The Cerium Effectmentioning

confidence: 91%

“…7,8 Particularly, Raman scattering and infrared transmission spectroscopies have proven to be valuable techniques in the determination of the rare-earth CF excitations in both electron-doped [9][10][11][12] and hole-doped cuprates. 13,14 Since the rare-earth ions are surrounded by oxygen ions, defects such as oxygen vacancies and interstitial oxygens affect their CF energy levels.…”

Section: Introductionmentioning

confidence: 99%

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Pr3+crystal-field excitation study of apical oxygen and reduction processes inPr2−

et al. 2004

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We present an infrared transmission Pr 3ϩ crystal-field study of as-grown, reduced, and oxygenated Pr 2Ϫx Ce x CuO 4Ϯ␦ single crystals and thin films. Excitations from the ground-state multiplet 3 H 4 to the 3 H 5 , 3 H 6 , 3 F 2 , and 3 F 3 excited multiplets are observed in all samples. In addition to the Pr 3ϩ regular sites, which remain unperturbed following the cerium doping or the oxygen content modifications, Pr 3ϩ sites are detected. A precise set of crystal-field parameters, which reproduces the energy and the symmetry of the levels, is determined. The reduction process, which drives the electron-doped cuprates superconducting, is discussed in detail and scenarios for the reduction mechanism and induced vacancies are proposed. In contrast to the common belief, the apical oxygen, which is clearly detected in all samples, is not removed in Pr 1.85 Ce 0.15 CuO 4 following reduction. This observation questions the role attributed to the apical oxygen removal in triggering the superconductivity.

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Section: The Cerium Effectmentioning

confidence: 91%