Karin L. Garcia

Temperature dependence of the switching field and its distribution function in Fe-based bistable microwires

The switching field distribution for magnetization reversal in a single Barkhausen jump of a bistable Fe-based amorphous microwire as well as its temperature dependence have been investigated in the temperature range from 77 to 450 K. Two processes have been identified to be responsible for the temperature dependence of the switching field: magnetostrictive volume domain wall pinning on stresses and relaxation effects due to local structural rearrangements. While at low temperatures, pinning on the atomic level defects plays the dominant role, magnetostrictive pinning becomes more important at intermediate temperatures. A simple model is proposed considering both energy contributions that fits reasonably well with experimental data and allows us to interpret additionally the observed temperature dependence of the switching field fluctuations.

Influence of the magnetoelastic mechanism on the fluctuating switching field of Fe-based amorphous microwires

The temperature dependence of the switching field and its fluctuations for a bistable Fe-based glass coated microwires family with magnetostriction values from 2/spl times/10/sup -6/ to 28/spl times/10/sup -6/ is presented in the temperature range 77-425 K. A simple model considering two energy contributions from magnetoelastic pinning and structural relaxation is considered to fit experimental data. Particularly, the contribution of magnetostriction and coating stresses to the temperature dependence of magnetoelastic term is analyzed in more detail. The relative magnetoelastic contribution is shown to increase with Fe content as magnetostriction increases, as well as with temperature. The contributions to magnetostriction from single-ion and two-ion mechanisms are also analyzed.

Single-Domain wall velocity, energy and shape during magnetization reversal in Fe-based bistable microwires

The domain wall dynamics during magnetization reversal process of glass-coated amorphous Fe77.5Si7.5B15 bistable microwire was considered. Its domain structure deriving from the magnetoelastic and shape anisotropies consists of an axial single domain and two closure domain structures at the ends, plus an outer radial-helical shell in its surface. This articles report the measured domain wall velocities, mobilities, and shape, which enables the determination of the domain wall energy per unit area, g, from direct observations of the domain wall length, L.