Eur. Phys. J. B 30, 45-51 (2002)
https://doi.org/10.1140/epjb/e2002-00356-9

Effective action approach to the Leggett's mode in two-band superconductors

¹ Institut de Physique, Université de Neuchâtel, 2000 Neuchâtel, Switzerland
² Bogolyubov Institute for Theoretical Physics, Metrologicheskaya Str. 14-b, Kiev, 03143, Ukraine

Corresponding author: ^a Sergei.Sharapov@unine.ch

Received: 10 May 2002
Published online: 19 November 2002

Abstract

We investigate a collective excitation (Leggett's mode) corresponding to small fluctuations of the relative phase of two condensates in two-band superconductor using the effective “phase only” action. We consider the possibility of observing Leggett's mode in MgB₂ superconductor and conclude that for the known at present values of the two-band model parameters for MgB₂ Leggett's mode arises above the two-particle threshold.