We have performed a calculation on the change of the critical temperature ${\mathit{T}}_{\mathit{c}}$ of a superconducting host with respect to the change of the concentration c of two-channel Kondo impurities in the limit of vanishing c. ${\mathit{T}}_{\mathit{c}}$ suppressions are found for both spin-singlet flavor-triplet and spin-triplet flavor-singlet pairings for temperatures as low as ${\mathit{T}}_{\mathit{K}}$/${\mathit{T}}_{\mathit{c}0}$>1, where ${\mathit{T}}_{\mathit{K}}$ and ${\mathit{T}}_{\mathit{c}0}$ are the Kondo temperature and the critical temperature of the host in the absence of impurities, respectively. The suppression is much larger for the spin-singlet flavor-triplet pairing. We also found empirically that (∂${\mathit{T}}_{\mathit{c}}$/∂c${)}_{\mathit{c}=0\mathrm{}}$ can be expressed as a product of two functions g(${\mathit{T}}_{\mathit{K}}$/T) and f(${\lambda }_0$,${\mathrm{\omega }}_0$), where ${\lambda }_0$ and ${\mathrm{\omega }}_0$ are electron phonon coupling and Einstein frequency, respectively.

• Received 5 July 1994

DOI:https://doi.org/10.1103/PhysRevB.50.15864