No abstract

We investigated the mutual induction effects between the d-wave and the s-wave components of order parameters due to superconducting fluctuation above the critical temperatures and calculated its contributions to paraconductivity and excess Hall conductivity based on the two-component stochastic TDGL equation. It is shown that the coupling of two components increases paraconductivity while it decreases excess Hall conductivity compared to the cases when each component fluctuates independently. We also found the singular behavior in the paraconductivity and the excess Hall conductivity dependence on the coupling parameter which is consistent with the natural restriction among the coefficients of gradient terms. Recently many experimental results indicate the mixed pairing symmetry of Cooper pairs in high-T c cuprates which consists of d-and s-wave-like components. 1, 2) Theoretically, it is shown that certain classes of microscopic models lead to dominant d-wave pairing with subdominant s-wave pairing. 7) Macroscopic properties of superconductors of these mixed symmetry can be studied by means of the Ginzburg-Landau (GL) thoery for two-component order parameter. Phenomenologically, Joynt 3) first introduced the GL free energy of two-component superconductors based on the group theoretical consideration. 4) Microscopic derivations of the corresponding two-component GL equations have been performed by several authors. 5,6,7,8) Due to those macroscopic arguments, it is shown that, in tetragonal lattice, the coexistence of the two components is not expected in the bulk, but the subdominant order parameter is induced by spatial variations because two components are coupled through "mixed gradient" term; this effect has been intensively investigated under the circumstances such as vortices, 9,8,10,11) impurities, 6)

We study the two-dimensional spin-charge separated Ginzburg-Landau theory containing U(1) gauge interactions as a semi-phenomenological model describing fluctuating condensates in high temperature superconductivity. Transforming the original GL action, we abstract the effective action of Cooper pair. Especially, we clarify how Cooper pair correlation evolves in the normal state from the point of view of spin-charge separation. Furthermore, we point out how Cooper pair couples to gauge field in a gauge-invariant way, stressing the insensitivity of Cooper pair to infrared gauge field fluctuation.