IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Mechanisms controlling coercivity in bulk amorphous Nd60Fe30Al10 ferromagnets
Autor/es:
J. M. LEVINGSTON; L. M. FABIETTI; S.E. URRETA
Lugar:
Buenos Aires
Reunión:
Encuentro; XI Encuentro CNEA "Superficies y Materiales Nanoestructurados; 2011
Resumen:
The magnetization switching mechanisms operating in Nd60Fe30Al10 ferromagnets areinvestigated. Thin ribbons (30–100 μm thick) and bulk pieces (cylinders 1–5 mm diameter)of the alloy are prepared by ultra fast quenching in two ways: by suction-casting intoa water chilled mould and by twin roller melt-spinning. General insight into the magneticbehavior of the alloys is gained from hysteresis loop measurements at temperatures between100 and 300 K and from room temperature magnetization relaxation curves. Forall the quenching conditions, coercivity steeply increases at low temperature. In cylindricalsamples, the temperature dependence of the intrinsic coercive field is consistent with thatpredicted by the strong domain wall pinning model. In ribbons, coercivity is attributed to acooperative switching mechanism operating in a superferromagnetic matrix, containing anhomogeneous distribution of small (_2 nm) interacting magnetic clusters. From the strongpinning model parameters, effective values for the exchange and anisotropy constants areestimated. Results are supported by microstructure, electron microscopy and magnetic viscosityobservations.