ScienceAsia 20 (1994): 135-143 |doi: 10.2306/scienceasia1513-1874.1994.20.135

EFFECTS OF DIFFERENT ALKALI METAL SUBSTITUTION ON THE INTERLAYER COUPLING IN "2212" BISMUTH SUPERCONDUCTORS

I.M. TANG,¹ S. LEElAPRUTE,¹ N. CHAICHIT,² J. LAKSANABOONSONG,² K. TREECHAIRUSMEE² AND C. ENGKAGUL³

ABSTRACT: The effects of systematic ( non isovalent ) substitutions of alkali metal ions ( Li, Na, K and Rb ) on the T_co's of the two layer bismuth superconductor Bi₂Sr₂CaCu₂0₂ are studied. It is found that the decrease in the optimal T, ( occurring at some optimal level of substitution) for each type of substitution correlates with the increase in the ionic size of the alkali metal. The results are interpreted within a framework of a model for high temperature superconductivity in which interlayer coupling of the order parameters in adjacent Cu0₂ layers plays an important role in enhancing the transition temperatures.

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1 High Temperature Superconductivity Laboratory, Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
2 Department of Physics, Faculty of Science, Silpakorn University, Nakorn Pathom 73000, Thailand.
3 Faculty ofSc'ence and Technology, Thammasat University, Rangsit Campus, Patum Thani 12121, Thailand.

Received Aug 1, 1994