Polarized x-ray absorption spectroscopy study of the symmetry of unoccupied electronic states near the Fermi level in the system

Abstract

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Polarized XANES study of the importance of inter-block vis-$agrave$-vis intra-block coupling in evolution of Tc in halide-molecule-intercalated Bi2Sr2CaCu2O8$minus$$\delta$ single crystals

“…This motivated the present study, in which we make use of the polarized XANES measurements at the O K and the Cu L 3 absorption edges. As is well known, polarization-dependent E (a, b) and E ∼ c measurements on well characterized single crystals yield quite reliable estimates of the itinerant hole density in the CuO 2 plane and that along the c-direction [20][21][22][23][24][25][26][30][31][32][33]. Our preliminary results in this regard have been reported earlier [34].…”

“…Neglecting the excitonic effects, one can conclude that these oxygen-derived 2p final states are located at the Fermi level [31,32]. The intensity of this pre-peak is known to be directly proportional to the amount of hole doping and is known to be a direct measure of density of the itinerant/doping holes [20][21][22][23][24][25][26][30][31][32] in these systems but not their T c [36].…”

“…Although the iodine intercalation appeared to have been thoroughly studied [16][17][18][19], we felt incontrovertible evidence in favour of conclusions drawn in the case of the mercury-halidedoped systems was lacking. Polarized x-ray absorption spectroscopy at the O K and Cu L 3 edges has proved to be a powerful tool for probing the nature and symmetry of the hole states in the superconducting cuprate perovskites [20][21][22][23][24][25][26][27][28][29][30][31][32][33]. This motivated the present study, in which we make use of the polarized XANES measurements at the O K and the Cu L 3 absorption edges.…”

Codimension one foliations of flat $ 3$-manifolds

“…Chen et al [7] have, however, convincingly shown from their fluorescence-yield (FY) study of the La 2−x Sr x CuO 4 system that while both the covalent and the doping holes possess a significant O 2p z character, likely to be associated with the apical O, the Cu 3d z 2 −r 2 states are virtually absent. Later on, studies carried out using bulk-sensitive fluorescence detection [11,12,14] also indicated the virtual absence of these states from Bi(2212). Just when a consensus seemed to be emerging on the absence of Cu 3d z 2 −r 2 holes when the measurements are done using the FY mode, Pellegrin et al [9] demonstrated the presence of a significant population of these states in the Tl(2223) system with the FY mode.…”

“…X-ray absorption spectroscopy and allied high-energy spectroscopy techniques have proved to be of great use in the study of the important question of the symmetry of the itinerant doping holes in various cuprate systems responsible for superconductivity; see, e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Most reports seem to agree that the O 2p and the Cu 3d holes have a predominantly in-plane symmetry, but with a significant population of out-of-plane O 2p holes.…”