The effect of damage on the superconducting and magnetic transition in ErRh4B4

Thin films of ErRh₄B₄, which exhibit both the superconducting and magnetic transitions observed in the bulk, were damaged by irradiation with 1.8 MeV α-particles. The dependence of T_c of the film on fluence, and the resulting resistance ratio, is very similar to that of A15 materials. The ferromagnetic transition is also rapidly depressed by damage. The results raise interesting questions concerning the band structure of cluster compound superconductors, the nature of the magnetic transition in ErRh₄B₄ and the generality of the sensitivity of cluster compounds to damage.