ScienceAsia 23 (1997): 359-369 |doi: 10.2306/scienceasia1513-1874.1997.23.359

EXPERIMENTAL STUDIES ON THE EFFECTS OF TRANSITION METAL DOPING IN OVERDOPED "2212" BISMUTH SUPERCONDUCTORS

S. LEELAPRUTE^a, LM. TANC^a,b AND T. OSOTCHAN^a,b

ABSTRACT: The depression of the T_c's of overdoped "2212" bismuth superconductors due to transition metal (TM) substitution is studied. Single phase Bi_1.55Pb_0.45Sr₂CaCu_2-xTM_xO_s+y ( TM = Zn, Fe, Ni and Co ) superconductors with varying hole concentrations were obtained by quenching in liquid nitrogen, superconducting pellets being annealed at different temperatures. It is seen that the T_c's decrease linearly with increasing substitUtion (once the influence of the varying hole concentration is taken into consideration) of the TM impurities. The rates of depression of Te due to non magnetic Zn²⁺ substitution and to magnetic Ni²⁺ substitutions are nearly the same. The magnitudes of the rates of depression dT I dx caused by different magnetic TM ion substitUtions appear to scale with the square of the magnetic moments formed on the ions. These behaviors are explained in the context of the spin fluctuation induced theory for high temperature superconductors.

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a Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
b Institute of Science & Techology for Research & Development Salaya Campus, Nakorn Pathom 73170, Thailand.

Received 28 November 1997