Effect of applied stress on remagnetization and magnetization profile of Co–Si–B amorphous wire

Abstract

Effect of the tensile stress, σ, on hysteresis loops of Co 72.5Si 12.5B 15 conventional (120 μm) amorphous wires with different length, l, (2⩽ l⩽10 cm) have been measured at the amplitude of applied field just above the switching field. The character of the hysteresis loops change drastically with the sample length, being attributed to the existence of a critical length, l c , found to be around 4 cm. Measurements performed by a short movable coil permit to obtain dependence of remanent magnetization, μ 0 M r, and coercivity, H c, on the position of this coil, L. At l> l c μ 0 M r( σ) dependence first shows a decrease and then increases with σ. Local hysteresis loops at l< l c without stress do not show a rectangular character even in the central region. It was found that by increasing the applied stresses initially, the flat local hysteresis loop measured for L=1.5 cm (at l=3 cm) becomes rectangular. This means that the application of tensile stress reduces the penetration depth of the closure domains, which results in the decreasing of the critical length. Stress dependence of μ 0 M r and H c should be understood in terms of the competition of magnetostatic and magnetoelastic energies. The correlation of the critical length with the magnetic anisotropies (i.e. magnetoelastic and shape anisotropies) is discussed.