Magnetic Interactions in Wiegand Wires Evaluated by First-Order Reversal Curves

Abstract

Wiegand wires exhibit a unique fast magnetization reversal feature in the soft layer that is accompanied by a large Barkhausen jump, which is also known as the Wiegand effect. However, the magnetic structure and interaction in Wiegand wires cannot be evaluated by conventional magnetization hysteresis curves. We analyzed the magnetic properties of Wiegand wires at various lengths by measuring the first-order reversal curves (FORCs) and by evaluating the FORC diagram from a series of FORCs. In particular, we used a FeCoV Wiegand wire with a magnetic soft outer layer, an intermediate layer, and a hard core. The magnetization of the various layers in the wire could be identified from the FORC diagrams. Furthermore, based on the interaction between multiple layers, the positive and negative polarity of the FORC distribution was clarified.

Magnetic Structure of Wiegand Wire Analyzed by First-Order Reversal Curves

“…The coercive forces of the major hysteresis loops of the Wiegand wire are plotted in Figure 4 b, which are represented by the red dotted lines in Figure 6 . The comparative analysis demonstrated that the coercive force of the major hysteresis loop of the Wiegand wire with equal diameter was consistent with the maximum intensity of the FORC distribution, ρ [ 21 ].…”

“…According to the magnetic structure of the 0.06 mm-diameter Wiegand wire, the inner layer was the hard layer and the outer layer was the soft layer. We analyzed the FORC diagrams of the Wiegand wires with diameters of 0.10, 0.14, 0.18, and 0.23 mm, and observed that their FORC diagrams were segmented into six or seven small regions with similar distributions, implying the existence of more than one coercivity component [ 21 ]. The distribution intensity of each small area of the FORC diagram increased with the increase in the diameter, as stated in Section 4.1 .…”

“…The analysis of the FORC curve and diagram of the 0.10mm-diameter Wiegand wire was presented as an example [ 21 ]. In Figure 13 a, μ 0 H b denotes the horizontal axis and μ 0 H a represents the vertical axis.…”

“…However, these studies did not explain the coercive force field distribution of each layer in detail. The magnetic structure of Wiegand wires with varying lengths were analyzed by FORC and the coercive force distribution and interactive force were analyzed in detail [ 21 ]. Contrary to the aforementioned studies, certain researchers state that the outer layer of the Wiegand wire is the hard layer, whereas the inner layer forms the soft layer [ 22 ].…”

“…We report the distribution of the coercive and interactive force fields in the Wiegand wire based on the wire diameter, which is evaluated in terms of the FORC diagram [ 20 , 21 ]. We conclusively demonstrate that the center core of the Wiegand wire is the hard magnetic part, whereas the outer layer is the soft layer exhibiting a lower coercive force.…”