Supercarrier density isotope effect manifestation in a multiband superconductor

Isotope effects in a multiband superconductor have been calculated with a leading interband pairing. Isotope effect exponents for the transition temperature (α  ), supercarrier density (αnαn), paired carrier effective mass (αmαm) and the penetration depth (αλαλ) on the whole doping scale have been obtained. It is found that supercarrier density isotope effect exists for the interband pairing having the same trend and the order of magnitude as α  . In contrast with the usual assumption αnαn plays then the decisive role in determining the penetration depth (superfluid stiffness) isotope effect together with the smaller αmαm contribution.