On mechanisms of domain switching in amorphous glass‐coated wires

Abstract

The study of the magnetic properties of amorphous wires is a topic of great interest because of their outstanding properties, such as the giant magnetoimpedance effect. The domain structure of the amorphous wire consists of an axially magnetized inner core and the outer shell. Taking into account that the giant magnetoimpedance effect is mainly a surface effect, the investigation of surface magnetic structure in the outer shell becomes a special topic. Discovering earlier the basic domain structures, here we demonstrate the original domain structures and mechanisms of magnetization reversal in Co-and Fe-rich glass-covered microwires. In particular, we focused on the temperature dependence of the magnetization reversal process. The original effect -the rearrangement of domain structure without the domain walls movement -was found.ß 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction The giant magnetoimpedance (GMI) effect is a topic of great interest in the field of applied magnetism owing to the large sensitivity of the total impedance to an applied magnetic field [1-8]. Our previous investigation using the magneto-optical Kerr effect (MOKE) showed that the surface magnetic structure has a great influence on the value of the GMI ratio [8]. In particular, it was shown that the change of circular magnetization is the essential process influencing GMI. Generally, the mechanism of the magnetization reversal process in microwires consists of nucleation of magnetic domain structures [9], magnetic domain-wall (DW) motion, domain-structure transformations, magnetization switching between different magnetization states, and coherent rotation of magnetization. Earlier our investigations were focused on the single or multidomain-wall motion [10] and formation of multidomain structure. However, as reported in the present work, this magnetization reversal consists not only of DW motion but also of domain-structure rearrangement which does not include the DW motion. Here, we demonstrate the unusual mechanism of domain-structure transformation of both DW motion and magnetization switching of domain structures.

Spiral magnetic domain structure in cylindrically-shaped microwires

“…We studied stress-annealed glass-coated microwires with the Fe 71.7 B 13.4 Si 11 Nb 3 Ni 0.9 composition 6 , 8 , 9 , a metallic nucleus diameter of d = 103 µm and a total diameter including the glass coating of D = 158 µm. The microwires were prepared by the Taylor-Ulitovsky method previously described elsewhere 10 , 11 .…”

“…In the case of circular domains 8 , the periodicity of the domain structure is determined by the interplay of the domain nucleation and the DW mobility. For the case of spiral domain structure, however, the magnetization reversal consists of the nucleation of a solitary inclined wedged domain and its subsequent movement along the surface of the microwire.…”

Review of Helical Magnetic Structures in Magnetic Microwires

“…It is significant that the direction of the inclination of the helical structure did not change the sign. Otherwise, we would be talking about an elliptical magnetic structure [90]. To reinforce the experimental results, the demonstrated the spiral magnetic structure, we performed a theoretical analysis.…”

“…The experimental configuration of the combination of the crossed axial-circular magnetic fields realized in the Fe-rich microwires (Fe 71.7 B 13.4 Si 11 Nb 3 Ni 0.9, metallic nucleus radius 50 µm, glass coating thickness 20 µm) gives another interesting type of helical domain structure [90]. Fixing the DC circular magnetic field, we changed the axial magnetic field in a narrow range of 2.75 Oe-2.85 Oe (Figure 4).…”

“…We assumed that, in the general case, the domain wall has the shape of an ellipse. Therefore, Reprinted with permission from [90].…”