Evidence for suppression of reentrant behavior with Co-substitution in a-Fe_90-xCo_xZr₁₀ alloys

Abstract

A detailed "zero-field" Mossbauer and ferromagnetic resonance (FMR) study of a-Fe_90-xCo_xZr¹⁰ alloys with 0 ≤x ≤10 reveals that (i) alloys with x ≤2 exhibit at low temperatures properties that are reminiscent of reentrant spin glass behavior (ii) for such alloys, the hyperfine field distribution P(H) is bimodal and comprises two Gaussian distributions and the peak-to-peak FMR linewidth, ΔH_pp, diverges exponentially for T<T_C (iii) for x ≥ 4, the low-field Gaussian component in P(H) and the divergence in ΔH_pp at low temperatures both get completely suppressed. These observations imply that the reentrant behavior gets progressively suppressed with partial replacement of Fe with Co. All the diverse aspects of the present results have been interpreted in terms of the ferromagnetic matrix plus finite spin clusters model.