X-ray photoemission spectroscopy of the 90 K superconductor Ba₂YCu₃O_7−δ

Abstract

The x-ray photoemission spectroscopic (XPS) data from different pelletized samples of the 90 K superconductor Ba2YCu3O7 _ s (where S~0.2) have been obtained. The valence band spectrum (recorded at 300 and 170 K), which is composed of contributions from both the Cu 3c? and O 2p levels, is compared with the full potential linearized augmented plane wave (FLAPW) calculated electronic density-of-states (DOS) reported by Massidda et al. and Mattheiss and Hamann. The experimental data indicate a relatively low DOS at the Fermi level. Detailed measurements of the core level Cu 2p, O Is, Ba 3d, 4d, and Y 3d spectra of the superconducting and related standard materials, are presented. Data for the superconducting material were recorded in the freshly prepared form as well as after scraping in situ. The Cu 2p core level, satellite, and Auger spectra for the various samples were carefully examined in order to assess the possibility of the presence of Cu3 + ions in Ba2YCu3O7 _s. It is observed that surface reaction in air to form carbonates and hydroxides occurs readily in the superconducting material.

Origin of superconductivity suppression in (Dy1−xPrChen1, Liu2, Lin3 et al. 1997Phys. Rev. B17140View full textAdd to dashboardCite

“…Based on the photoemission studies by Iqbal et al, it is suggested that this peak arises from the absorption of hydrides, water, and CO 2 on surface. 44 The Pr M 45 -edge and Cu L 23 -edge x-ray-absorption nearedge-structure x-ray-fluorescence-yield spectra for a series of (Dy 1Ϫx Pr x )Ba 2 Cu 3 O 7Ϫ␦ compounds in the energy range 925-960 eV are shown in Fig. 3.…”

Enhancement of Zero Resistance Temperature above 90 K and Hole Distribution in (Hg0.5Pb0.5)Sr2(Ca0.7Y0.3)Cu2O7-δ via Chemical Substitution of Ba into Sr Sites

“…On the basis of their X-ray photoemission studies, Iqbal et al . suggested that these peaks are due to absorption of hydrides, water, and CO 2 on the surface …”

“…On the basis of their X-ray photoemission studies, Iqbal et al suggested that these peaks are due to absorption of hydrides, water, and CO 2 on the surface. 24 In Figure 9 are shown the Cu L 23 -edge X-ray-absorption nearedge-structure X-ray-fluorescence-yield spectra for the series of (Hg 0.5 Pb 0.5 )(Sr 2-x Ba x )(Ca 0.7 Y 0.3 )Cu 2 O 7-δ samples with x ) 0-0.5. As noted from Figure 9, the Cu L 23 -edge absorption spectra are asymmetric with two shoulders at the high-energy side of the main peaks.…”

Enhancement of critical Pr ion concentration (xcr) in (La1−xPrx)Ba2Cu3Oz

“…This change is related to a spectral weight transfer of states from the UHB to doping-induced hole states near the Fermi level. 65 Figure 8 presents the PrM 45 -edge and CuL 23 -edge x-rayfluorescence-yield spectra for the series of (La 1Ϫx Pr x )Ba 2 Cu 3 O z compounds with xϭ0, 0.1, 0.2, 0.3, 0.5, and 0.6 in the photon energy range of 920-960 eV. As marked on the top of Fig.…”