Possible Spin-Singlet Superconductivity in (TMTSF)2X:
Superconducting Transition Temperature in a Magnetic Field
Abstract
We study the transition temperature Tc(H) of a quasi-one-dimensional (Q1D)
superconductivity which is derived from the quantum effect of electron motion
in a strong magnetic field. We calculate Tc(H) of both isotropic and
anisotropic superconductivity by taking account of the optimal momentum of the
Cooper pairs and the effect of higher harmonic terms along the second conducting
axis in the tight-binding model. We find that, although Tc(H) of the
spin-singlet superconductivity is strongly suppressed by the Zeeman effect,
the suppression of Tc(H) is not very severe if we take the optimal
pair-momentum and the higher harmonic into account. The obtained Tc(H) for
the spin-singlet superconductivity is consistent with the experimental results
in TMTSF salts.
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