The dependence of the critical temperature on impurity concentration is calculated for a model of a tetragonal high- superconductor described in a previous paper [A. A. Abrikosov, Phys. Rev. B 52, R15 738 (1995)] under conditions when the odd ( symmetry) order parameter is favorable for a clean substance. The critical temperature decreases rapidly with increasing impurity concentration according to the general pair-braking formula and tends to zero at a critical concentration. Since, however, the critical temperature for the phase with an even order parameter is only weakly influenced by impurities, it eventually exceeds the of the odd phase, and this means a phase transition to the even phase. The curve is expected to have a kink and a long tail.
- Received 1 December 1995
- Published in the issue dated 1 April 1996
© 1996 The American Physical Society