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Effective action approach and Carlson-Goldman mode in d-wave superconductors

Sergei G. Sharapov·Hans Beck
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Abstract

We theoretically investigate the Carlson-Goldman (CG) mode in two-dimensional clean d-wave superconductors using the effective ``phase only'' action formalism. In conventional s-wave superconductors, it is known that the CG mode is observed as a peak in the structure factor of the pair susceptibility $S(Ω, \mathbf{K})$ only just below the transition temperature T_c and only in dirty systems. On the other hand, our analytical results support the statement by Y.Ohashi and S.Takada, Phys.Rev.B {\bf 62}, 5971 (2000) that in d-wave superconductors the CG mode can exist in clean systems down to the much lower temperatures, $T \approx 0.1 T_c$. We also consider the manifestations of the CG mode in the density-density and current-current correlators and discuss the gauge independence of the obtained results.

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Sergei G. Sharapov, Hans Beck. 2002-01-18. Effective action approach and Carlson-Goldman mode in d-wave superconductors. https://doi.org/10.1103/physrevb.65.134516

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