Switching mechanism in Co based amorphous wire

Abstract

To get a deeper insight into the mechanism involved in the flux reversal of Co based wire we have tickled the wire with an ac field of smaller amplitude than the switching field, H*, and observed the signal induced in a pancake coil moved along the wire, vibrated a small coil along the wire and observed the induced signal, and taken the temperature dependence of normalized saturation magnetization, Ms, and H*. No signal was observed in the pancake coil in the tickling experiment. A signal that has peak values close to the wire ends, but practically zero in the central region, was observed in the vibrating coil. The variations of Ms and H* with temperature only show a correlation. The results of the above experiments suggest that for Co based wire the most reasonable mechanism for the flux switching is nucleation of a free wall other than the depinning of residual reverse domains at the wire ends.

Tuning of Magnetoimpedance Effect and Magnetic Properties of Fe-Rich Glass-Coated Microwires by Joule Heating

“…The magnetization distribution of magnetic wires is commonly discussed considering the contribution of the exchange energy tending the axial magnetization alignment, magnetoelastic and induced magnetic anisotropies [ 67 , 68 , 70 , 78 ]. The peculiarity of Joule heating is that it involves sample heating in the presence of a circumferential magnetic field, H circ , created by a current flowing through the sample [ 26 , 67 ], given as: H circ = Ir /2 πR 2 where r is radial distance, R - microwire metallic nucleus radius.…”

“…Domain structures of magnetic wires are commonly described in terms of a core-shell model [ 36 , 37 , 78 , 79 ]. In terms of such a model, the domain structure of magnetically bistable microwires is described as consisting of a single axially magnetized domain surrounded by an outer domain shell with transverse (either radial or circumferential) magnetization.…”

Development of Co-Rich Microwires with Graded Magnetic Anisotropy

“…The modification of the hysteresis loops of the studied microwires must be related to the magnetic domain structure of microwires, which is affected by the λ s -value and sign, the internal stresses distribution, and the shape magnetic anisotropy. Thus, the axial magnetization alignment promoted by the exchange energy contribution is especially relevant for the case of thin and long enough magnetic wires due to high shape anisotropy [ 27 , 73 , 74 ]. However, in Co-rich magnetic microwires with λ s < 0, the presence of internal stresses is another factor that affects magnetoelastic anisotropy, K me given by Equation (1).…”

“…Additionally, in most parts of the metallic nucleus volume (roughly up to r ~0.85 R , where R is the metallic nucleus radius), the axial component, σ z , is approximately an order of magnitude higher than σ φ and σ r [ 75 , 76 , 77 , 78 , 79 , 80 , 81 ]. Such a character of internal stress turns the magnetization of Co-rich microwires with λ s < 0 to a circumferential direction [ 49 , 73 , 74 ].…”

“…In terms of the core-shell domain structure model, the modification in remanent magnetization, M r /M o , along the microwire can be attributed to the change in the inner axially magnetized core radius, R c , considering its relationship with M r /M 0 , given as [ 27 , 73 , 74 ]: R c = R ( M r / M 0 ) 1/2 , where R is the metallic nucleus radius.…”