Dielectric versus magnetic pairing mechanisms in high-temperature cuprate superconductors investigated using Raman scattering.
We suggest, and demonstrate, a systematic approach to the study of cuprate superconductors, namely, progressive change of ion size in order to systematically alter the interaction strength and other key parameters. R(Ba,Sr)2Cu3Oy (R={La,…,Lu,Y}) is such a system where potentially obscuring structural changes are minimal. We thereby systematically alter both dielectric and magnetic properties. Dielectric fluctuation is characterized by ionic polarizability while magnetic fluctuation is characterized by exchange interactions measurable by Raman scattering. The range of transition temperatures is 70-107 K, and we find that these correlate only with the dielectric properties, a behavior which persists with external pressure. The ultimate significance may remain to be proven, but it highlights the role of dielectric screening in the cuprates and adds support to a previously proposed novel pairing mechanism involving exchange of quantized waves of electronic polarization.
MacDiarmid Institute, SCPS, Victoria University, P.O. Box 600, Wellington 6140, New Zealand.
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Mallett
Karlsruhe Institute of Technology, Postfach 3640, Karlsruhe 76021, Germany.
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Wolf
IMEM-CNR, Institute of Materials for Electronics and Magnetism, 43124 Parma, Italy.
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Gilioli
IMEM-CNR, Institute of Materials for Electronics and Magnetism, 43124 Parma, Italy.
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Licci
MacDiarmid Institute, SCPS, Victoria University, P.O. Box 600, Wellington 6140, New Zealand.
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Williams
MacDiarmid Institute, SCPS, Victoria University, P.O. Box 600, Wellington 6140, New Zealand.
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Kaiser
Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501, USA.
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Ashcroft
MacDiarmid Institute, P.O. Box 31310 Lower Hutt, New Zealand.
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Suresh
MacDiarmid Institute, P.O. Box 31310 Lower Hutt, New Zealand.
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Tallon