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Magnetic domain walls and pulsed magnetization reversal in amorphous Fe40Ni40P14B6 ribbon under tension

1980; Elsevier BV; Volume: 20; Issue: 3 Linguagem: Inglês

10.1016/0304-8853(80)90442-4

1873-4766

Paul Williams, J.E.L. Bishop,

Metallic Glasses and Amorphous Alloys

Magnetization reversal has been studied in long ribbons of Metglas 2826 under tension. At low fields propagating head-on domain boundaries of the Sixtus-Tonks type were observed. Measurements of their lengths, of order 20 to 50 cm, together with a simple magnetostatic model of their structure, yield values of the specific domain wall surface energy γ = 3.8 × 10-8 σ12 J m-2 for tensile stress σ Pa. A value A= 5.6 × 10-12Jm-1 for the exchange constant follows. The low-fi eld mobility of these domain walls shows no evidence of relaxation damping at speeds below 1.2 m s-1. The threshold field at which reverse domains nucleate is found to be proportional to the square root of the tension. At high fields (>200 A m-1) the rough surface of the ribbon (the surface that came in contact with the quenching wheel during manufacture) reverses first and saturates at about the same time as the smooth surface begins to reverse and the volume reversal rate peaks. A simple quantitative model of the high field reversal process satisfactorily predicts both the surface and volume reversal rates. It yields a consistent value βR = 14 kg m-2s-1 for the relaxation damping constant at wall speeds in excess of 13 m s-1 and estimates the number of reversal nuclei in accord with Yagi and Anayama.