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Title: SCALING BEHAVIOR AT THE INSULATOR-METAL TRANSITION IN BI2SR2(CAZR1-Z)CU2O8+Y WHERE R IS A RARE-EARTH ELEMENT
Authors: QUITMANN, C ×
ANDRICH, D
JARCHOW, C
FLEUSTER, M
BESCHOTEN, B
GUNTHERODT, G
Moshchalkov, Victor
MANTE, G
MANZKE, R #
Issue Date: 1992
Publisher: AMERICAN PHYSICAL SOC
Series Title: Physical review. B, Condensed matter vol:46 issue:18 pages:11813-11825
Conference: date:MV LOMONOSOV STATE UNIV,DEPT PHYS,HIGH TC SUPERCOND LAB,MOSCOW 119899,USSR; UNIV KIEL,INST EXPTL PHYS,W-2300 KIEL 1,GERMANY
Abstract: We report on the details of the insulator-metal transition (IMT) induced in Bi2Sr2(CazR1-z)Cu2O8+y (R = Y, Gd, Nd) by Ca2+ doping. The resistivity in the insulating regime is analyzed using a generalized hopping approach based on the connectivity criterion. This enables us to estimate the dependence of the localization radius a(H) on the Ca concentration independent of dimensionality. Insulating samples with a Y content not too far from the critical concentration z(C) = (0.43 +/- 0.02) show metallic conduction at high temperature and hopping conduction at low temperature. This shows the coexistence of delocalized and localized states separated by a disorder-induced mobility edge. Ultraviolet-photoemission-spectroscopy (UPS) spectra give evidence for both a shift in the Fermi level to lower energies and the development of new states at the Fermi level. The existence of a mobility edge together with the shift in E(F) upon Ca2+ doping shows that the transition is probably of the Anderson type. We present a schematic picture for the density of states in the vicinity of E(F) based on the results of spectroscopic and transport data. For this density of states we calculate the electrical resistivity using the Kubo-Greenwood formula. The results are in good qualitative agreement with the experiments. At the IMT the localization radius diverges and the metallic conductivity vanishes following a scaling law sigma = sigma0 {1 -z/z(C)}eta, with a critical exponent eta = 1 A.
ISSN: 0163-1829
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Solid State Physics and Magnetism Section
× corresponding author
# (joint) last author

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