Coexistence of Various Nd-Rich and Fe-Rich Fe-Nd Short Range Orderings In Bulk Glassy Nd₆₀Fe₃₀Al₁₀ Hard Magnets

Abstract

Bulk Nd₆₀Fe₃₀Al₁₀ metallic glasses are found to exhibit a complex magnetic behavior at very low temperatures related to the coexistence of various Nd-rich and Fe-rich magnetic short range orderings, as evidenced by AC-susceptibility studies in combination with hysteretic loops at fields up to 30 T . Above 80 K the magnetic behavior is shown to correlate with Stoner-Wohlfarth hysteresis loops with pronounced thermal activation effects. These observations suggest the existence of an Fe-rich Fe–Nd hard magnetic ’phase’ formed by an ensemble of randomly oriented uniaxial magnetic nanoentities embedded in a Nd-rich matrix. The exchange coupling and development of a large axial crystal field anisotropy at very low temperatures and the uncoupling above 70 K of the Fe-rich Fe–Nd hard magnetic phase to the Nd-rich matrix appears to be at the origin of the observed overall magnetic behavior.