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arXiv · 0912.2481

Pairing competition in a quasi-one-dimensional model of organic superconductors (TMTSF)$_{2}X$ in magnetic field

Hirohito Aizawa·Kazuhiko Kuroki·Yukio Tanaka
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Abstract

We microscopically study the effect of the magnetic field (Zeeman splitting) on the superconducting state in a model for quasi-one-dimensional organic superconductors (TMTSF)$_{2}X$. We investigate the competition between spin singlet and spin triplet pairings and the Fulde-Ferrell-Larkin-Ovchinnikov(FFLO) state by random phase approximation. While we studied the competition by comparison with the eigenvalue of the gap equation at a fixed temperature in our previous study (Phys. Rev. Lett. \textbf{102} (2009) 016403), here we obtain both the $T_c$ for each pairing state and a phase diagram in the $T$(temperature)-$h_z$(field)-$V_y$(strength of the charge fluctuation) space. The phase diagram shows that consecutive transitions from singlet pairing to the FFLO state and further to $S_z=1$ triplet pairing can occur upon increasing the magnetic field when $2k_{F}$ charge fluctuations coexist with $2k_{F}$ spin fluctuations. In the FFLO state, the singlet d-wave and $S_{z}=0$ triplet $f$-wave components are strongly mixed especially when the charge fluctuations are strong.

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Hirohito Aizawa, Kazuhiko Kuroki, Yukio Tanaka. 2009-12-13. Pairing competition in a quasi-one-dimensional model of organic superconductors (TMTSF)$_{2}X$ in magnetic field. https://doi.org/10.1143/jpsj.78.124711

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