Origin of the superconducting transition suppression under La substitution

Determine whether the suppression of superconductivity in La-substituted Ce1-xLaxRh2As2 is quantitatively explained by anisotropic superconducting gap symmetry through the Abrikosov-Gorkov impurity-pair-breaking mechanism.

Background

La substitution rapidly suppresses Tc in Ce1-xLaxRh2As2, an effect attributed primarily to disorder-induced pair breaking rather than to the modest negative effective pressure caused by lattice expansion. Such sensitivity is consistent with unconventional superconductivity and potentially with a strongly anisotropic gap that changes sign.

The authors compare the data with the Abrikosov-Gorkov model, which could associate the Tc reduction with anisotropic gap symmetry, but state that the available analysis does not yield a reasonable conclusion. Thus, the relationship between the observed disorder sensitivity and the superconducting gap structure remains unresolved.

References

While the Abrikosov-Gorkov model applied to our experimental data might associate the reduction of $T_c$ with an anisotropic gap symmetry, we could not draw a reasonable conclusion.

— La substitution studies on the heavy-fermion superconductor CeRh$_2$As$_2$  (2609.17080 - Sankar et al., 15 Sep 2026) in Section Discussion