Revisiting magnetization processes in granular hard magnetic materials

Alexey Dobrynin , Vitoria M.T.S. Barthem (1) , Dominique Givord (2)

1 IF / UFRJ - Instituto de Física da Universidade Federal do Rio de Janeiro
2 NEEL - MNM - Micro et NanoMagnétisme

We show that the generally accepted demagnetizing field corrections are not applicable to the broad class of modern granular magnetic materials, where magnetization reversal occurs via discrete switching of the moments of individual grains, and thus the self-demagnetizing field of a given grain is proportional to the spontaneous magnetization Ms, not to the sample magnetization M. This leads to the fact that the self-demagnetizing field must be considered as a contribution to the coercive field and that the slope of the magnetization variation is higher than the classical demagnetizing field slope. This description of demagnetization processes is confirmed by numerical modeling.

Mots clés: Demagnetizing field; magnetization processes; hard magnetic materials; magnetic recording media

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Alexey Dobrynin, Vitoria M.T.S. Barthem, Dominique Givord. Revisiting magnetization processes in granular hard magnetic materials. Applied Physics Letters, 2009, 95 (5), pp.052511. ⟨10.1063/1.3193543⟩. ⟨hal-00439602⟩