On one-dimensional superconductivity in two-band conductors
Abstract
The problem of conductivity (at T > 0) and superconductivity criteria (at T = 0) is considered for one-dimensional two-band conductors. It is found that the superconducting transition does not depend on the sign of the interband interaction constant λ and depends considerably on the sign of the intraband interaction constant γ. For γ < 0, the system is superconducting for any value of λ. For γ > 0, the superconducting state is possible if λ exceeds a certain critical value which is determined by the value of γ. The effect of random impurity centers on the conducting properties of the system is investigated. It is shown that in the case of a weak interaction between charge carriers (for which a quantitative criterion has been established), impurities lead to carrier localization. When the interaction between charge carriers is strong enough, localization does not take place, and the system can go over to the superconducting state in the presence of impurities. The effect of interband transitions on the phase diagram at T = 0 is investigated and the conditions under which interband transitions do not hinder the superconductivity of the system are established.