Effect of interchain electron transfer on the phase transition of quasi-one-dimensional electron systems

The critical temperatures of phase transitions of quasi-one-dimensional systems are evaluated by assuming electron transfer between chains with intrachain interactions represented by the model of Bychkov, Gor'kov, and Dzyaloshinskii. We examine only the case of g ₁ > 0, where the renormalization group theory for an isolated chain gives reliable results. For small electron transfer energy t, the transition temperature T _c is an increasing function of t. As t gets larger, however, T _c becomes a decreasing function of t due to the tunneling of individual electrons, which destroys the coherent pairing states. A symmetry is found to exist between T _c of the triplet superconductivity and that of the spin density wave state which have the highest critical temperatures in the regions of g ₁ > 2g ₂ and g ₁ < 2g ₂, respectively.