The Barkhausen Effects and Nano-System Magnetizations in Fe

Obata, Shuji

doi:10.2320/matertrans.maw201305

Cited by 5 publications

(2 citation statements)

References 25 publications

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“…The steps of the external magnetic eld, ΔH, are related to the coercivity. As described in our previous paper 5) , the physical cause of the coercivity is related to the delay of the response of the Barkhausen jump [15][16][17][18][19] by the applied magnetic eld. From the temperature dependence of the step of the effective magnetic eld that was introduced by eq.…”

Section: Discussion and Summarymentioning

confidence: 78%

Temperature Dependence of the Magnetic Hysteresis Curves in Magnetic Multilayers

et al. 2017

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We performed a theoretical study of the magnetic hysteresis curves for an Fe 3 O 4 -based magnetic multilayer. Such a systems are known as the spin valves in the spintronics eld. To investigate the temperature dependence of the magnetization process in such a system, we extend the retarded trace method and plot the magnetic hysteresis curve by computer simulation. Our results show very good agreement with the experimental data.

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Section: Discussion and Summarymentioning

confidence: 78%

Temperature Dependence of the Magnetic Hysteresis Curves in Magnetic Multilayers

et al. 2017

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“…In aligned carbon nanotubes systems containing iron nanowires, 1) presence of quantized Barkhausen jump 2) has been confirmed. Usually, cause of quantized Barkhausen jump is believed to depinning of domains or magnetization reversal.…”

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confidence: 70%

Dual Control Theory of Spintronics

2014

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For explaining about the quantized Barkhausen jump that is observed in iron nanowires system, we introduced the two type spin Josephson junction models. One type of these system are composed of the sandwich structure by FM (ferromagnet)/AM (anti ferromagnet)/FM junction, and its dual junction is consists of the sandwich structure by AF/FM/AF junction. In order to apply to spintronics technology these spin junction models, we constructed a dual control theory by pseudo-spin quantum Hall effect. 3) in the sandwich structure of the FM (ferromagnet)/ AM (antiferromagnet)/FM junction that operates using single domain wall tunneling. As another type of these models which is a dual models of FM/AF/FM junction, we have devised model of antiferromagnetic spin Josephson junction device in the sandwich structure of the AM/FM/AM junction that operates using single magnetic moment tunneling. Figure 1(a) shows the schematic of FM/AF/FM junction.In the FM/AF/FM junction of Fig. 1(a), Antiferromagnetic material (spin-dielectric material) barrier that sandwiched between the ferromagnetic material is functions as a spin capacitor. In Fig. 1(b), shows the conceptual diagram of a spin capacitor. 4,5) In Fig. 1(b), up spin state "¼" can be considered as negative spin charge "ÀQ 0 s " in Fig. 1(c). Similarly, in Fig. 1(b) down spin state "←" can be considered as positive spin charge "þQ 0 s " in Fig. 1(c). Here +S, ¹S are total amount of positive and negative spin-charge (spin magnetic moment) in the spin electrode respectively. In Figs. 2(a)2(d) below shows stepwise tunneling process of single domain wall. In Fig. 2(a), the single domain wall not occur in the electrode. In the negative spin electrode of Fig. 2(b), if the single domain wall is generate by quantum fluctuations, case of the antiferromagnetic layer which is close to this, magnetic reversal occurs, single ferromagnetic magnetic moment are occurs. In Fig. 2(c), the single ferromagnetic magnetic moment transitions to one unit to the positive electrode side. In Fig. 2(c), the single domain wall reaches the positive electrode side, tunneling is completed.As a model for such ferromagnetic spin Josephson systems, first, we consider Hamiltonian of the Heisenberg XXZ spin models 4) as follows:The first term is the Zeeman energy due to the z-component of external magnetic field H z ðjÞ, where ® 0 B is Bohr magneton in E-H corresponding, the second first term describe the Ising spin energy, and the third term describe the XY spin energy. We can rewrite the Hamiltonian from an analogy of Josephson junctions 4,5) as follows:

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Magnetic Noise ‐ Barkhausen Effect

Pardavi‐Horváth

2014

Wiley Encyclopedia of Electrical and Electronics Engineering

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The change of the magnetic state of a ferromagnetic body under the effect of a slowly changing externally applied magnetic field is a complex process, involving reversible and irreversible changes of the magnetization. Due to irreversible magnetization processes, the change of the magnetic state is accompanied by losses, manifested by the presence of magnetic hysteresis. The physical origin of the losses is that a real material has a microstructure, material defects, and internal stresses responsible for the details of the hysteresis loop. The magnetization changes discontinuously in space and in time by jumps from defect to defect, giving rise to magnetic noise. This process and the corresponding noise are named after its discoverer, H. Barkhausen (1919) as Barkhausen jumps and Barkhausen noise . Superconducting materials display s imilar phenomena. The Barkhausen noise spectrum is an important non‐destructive characterization tool in metallurgy and manufacturing. In the following the physical mechanism, measurement and instrumentation, and applications of the Barkhausen noise are reviewed.

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The Barkhausen Effects and Nano-System Magnetizations in Fe

Cited by 5 publications

References 25 publications

Temperature Dependence of the Magnetic Hysteresis Curves in Magnetic Multilayers

Temperature Dependence of the Magnetic Hysteresis Curves in Magnetic Multilayers

Dual Control Theory of Spintronics

Magnetic Noise ‐ Barkhausen Effect

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