SPIN-DENSITY-WAVE VERSUS SUPERCONDUCTING FLUCTUATIONS FOR QUASI-ONE-DIMENSIONAL ELECTRONS IN 2 CHAINS OF TOMONAGA-LUTTINGER LIQUIDS

We study possible states at low temperatures by applying the renormali zation group method to two chains of Tomonaga-Luttinger liquids with b oth repulsive intrachain interactions and interchain hopping. As the e nergy decreases below the hopping energy, three distinct regions I, II I, and II appear successively depending on properties of fluctuations. The crossover from the spin-density wave (SDW) state to superconducti ng (SC) state takes place in region UI where there are the excitation gaps of transverse charge and spin fluctuations. The competition betwe en SDW and SC states in region III is crucial to understanding the pha se diagram in the quasi-one-dimensional organic conductors.