654 research outputs found
Temperature dependence of the doping holes in lsco superconductor studied by polarized Cu L-X-ray absorption
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UvA-DARE (Digital Academic Repository) Link to publication Citation for published version (APA)
No full textEffect of impurity phases on the anisotropic properties of CeNiSn Nakamoto, G.; Link to publication Citation for published version (APA): Nakamoto, G., Takabatake, T., Bando, Y., Fujii, H., Izawa, K., Suzuki, T., ... Menovsky, A. A. (1995). Effect of impurity phases on the anisotropic properties of CeNiSn. [206][207][840][841][842][843
Decrease of Itinerant Holes Near the Metal to Insulator Crossover in Superconducting La1.85Sr0.15CuO4
No full textPolarized Cu L-edge X-ray absorption spectra (XAS) measurements of the unoccupied electronic state of 3d(x)2-(y)2 symmetry in superconducting La1.85Sr0.15CuO4 Single crystals show a temperature dependent anomalous decrease of the density of itinerant holes below similar to 100 K. The anomalous temperature coincides with the temperature of the metal to insulator (MI) transition and local lattice distortions in the CuO2 plane. The results give direct evidence of decrease of itinerant states in the CuO2 plane due to local lattice distortions across the MI crossover in the normal state
The magnetic torque of the heavy-fermion Upd2Ga3
No full textThe magnetic torque of the heavy-fermion Upd2Ga3 Sullow, S.; Janossy, B.; van Vliet, G.E.L.; Nieuwenhuys, G.J.; Menovsky, A.A.; Mydosh, J.A. Published in: Journal of Physics-Condensed Matter DOI: 10.1088/0953-8984/8/6/013 Link to publication Citation for published version (APA): Sullow, S., Janossy, B., van Vliet, G. E. L., Nieuwenhuys, G. J., Menovsky, A. A., & Mydosh, J. A. (1996). The magnetic torque of the heavy-fermion Upd2Ga3. Journal of General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract. The basal-plane anisotropy of the antiferromagnetic phase of the hexagonal heavy-fermion superconductor UPd 2 Al 3 has been studied via the magnetic torque. Torque measurements were performed as functions of magnetic field and angle, with the field rotated in the a-b-plane, at temperatures between 4.2 and 30 K and in fields of up to 20 T. We interpret our results within a mean-field model and derive expressions for the basal-plane anisotropy energy. Further, we studied the anisotropy and temperature dependence of the metamagnetic transition of UPd 2 Al 3 at 18 T and we discuss its nature
Evidence of Redistribution of the Itinerant holes Below Tc in Bi2Sr2CaCu2O8 Superconductors: A Polarised X-ray Absorption Study
No full textThe microscopic electronic structure of high-quality superconducting Bi2Sr2CaCu2O8+y (Bi2212) single crystals has been investigated in the normal and superconducting states by polarized x-ray-absorption (XAS) measurements. The O K-edge XAS results led us to conclude the presence of a significant density of p(z) symmetry orbitals for itinerant holes. We observed a reproducible increase in the number of O 2p(x,y) itinerant holes accompanied by a decrease of the O K XAS transition in the upper Hubbard band (covalent holes) while going from the normal to the superconducting state of the system. The increase of O 2p,, holes was confirmed by an increase in the 3d(9)L/3d(9) ratio estimated from Cu L(3) XAS measurements. This is in agreement with earlier inverse photoemission measurements and constitutes evidence for the redistribution of the itinerant holes below the transition temperature (T-c)
The Out-of-Plane Cu 3d and O 2p Holes in the Bi2212 System
No full textThe polarisation dependent X-ray absorption measurements (XAS) have been made below the transition temperature of Bi2Sr2CaCu2O2+y (Bi2212) superconducting system. The results suggest a negligible amount of Cu 3dz2-r2 symmetry holes but give a strong evidence of presence of a significant amount of pz symmetry holes. The polarisation dependent Cu L3 and O K spectra are reported both in superconducting as well as in normal state of the Bi2212 system
Direct observation of the Zhang-Rice singlets in high-temperature superconductors
No full textFrom a spin-resolved photoemission study on the Bi2Sr2CaCu2O8+δ superconductor, we show experimentally that the first ionization state is of nearly pure singlet character. This is true both above and below the superconducting transition and in the presence of doping and band formation. This provides direct support for the existence and stability of Zhang-Rice singlets in high-temperature superconductors, justifying the ansatz of single-band models. Moreover, we establish this technique as an important probe for a wide range of cuprates and strongly correlated materials
Crossing the Gap from p- to n-Type Doping: Nature of the States near the Chemical Potential in La 2-xSrxCuO4 and Nd2-xCexCuO4
No full textWe report on an x-ray absorption and resonant photoemission study on single crystals of the high-T-c cuprates La2-xSrxCuO4 and Nd2-xCexCuO4-delta. Using an intrinsic energy reference, we find that the chemical potential of La2-xSrxCuO4 lies near the top of the La2CuO4 valence band whereas in Nd2-xCexCuO4-delta it is situated near the bottom of the Nd2CuO4 conduction band. The data clearly establish that the introduction of Ce in Nd2CuO4 results in electrons being doped into the CuO2 planes. We infer that the states closest to the chemical potential have a Cu 3d(10) singlet origin in Nd2-xCexCuO4-delta and a 3d(9) (L) under bar singlet origin in La2-xSrxCuO4
Polarized XANES Study of Cu L3 Edges of Bi-2212 Superconducting Single crystals Using Total and Fluorescence Yield Techniques
No full textXANES with polarized synchrotron light is now established to be one of the important techniques for the study of the electronic structure of high-T-c superconductors in order to find out the symmetry of holes and their implication to the theoretical models proposed to explain superconductivity in these cuprates. The XANES spectra are measured by two methods in the soft X-ray region, namely, total yield (TY) and fluorescence yield (FY) methods, which give different results with respect to out-of-plane Cu 3d(z(2)) symmetric holes. The reason of this discrepancy is not quite clear. Polarized XANES measurements on Bi-2212 single crystals at the Cu L(3) edge by the TY and FY methods are reported and the results are discussed in detail
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