A Novel Computational Method to Identify/Analyze Hysteresis Loops of Hard Magnetic Materials

In this study, a novel computational method capable of reproducing hysteresis loops of hard magnetic materials is proposed. It is conceptually based on the classical Preisach model but has a completely different approach in the modeling of the hysteron effect. Indeed, the change in magnetization caused by a single hysteron is compared here to the change in velocity of two disk-shaped solids elastically colliding with each other rather than the effect of ideal geometrical entities giving rise to so-called Barkhausen jumps. This allowed us to obtain a simple differential formulation for the global magnetization equation with a significant improvement in terms of computational performance. A sensitivity analysis on the parameters of the proposed method has indeed shown the capability to model a large class of hysteresis loops. Moreover, the proposed method permits modeling of the temperature effect on magnetization of neodymium magnets, which is a key point for the design of electrical machines. Therefore, application of the proposed method to the hysteresis loop of a real NdFeB magnet has been proven to be very accurate and efficient for a large temperature range.

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Developing a reference material set for the magnetic properties of NdFeB alloy-based hard magnetic materials

Reference materials ◽

10.20915/2077-1177-2019-15-1-21-27 ◽

2019 ◽

Vol 15 (1) ◽

pp. 21-27

Author(s):

E. A. Volegova ◽

T. I. Maslova ◽

V. O. Vas’kovskiy ◽

A. S. Volegov

Keyword(s):

Magnetic Properties ◽

Magnetic Materials ◽

Permanent Magnets ◽

Magnetic Loss ◽

Magnetic Hysteresis ◽

Hysteresis Loops ◽

Magnetic Hysteresis Loop ◽

Magnetic Characteristics ◽

Hard Magnetic Materials ◽

Certified Values

Introduction The introduction indicates the need for the use of permanent magnets in various technology fields. The necessity of measuring the limit magnetic hysteresis loop for the correct calculation of magnetic system parameters is considered. The main sources of error when measuring boundary hysteresis loops are given. The practical impossibility of verifying blocks of magnetic measuring systems element-by-element is noted. This paper is devoted to the development of reference materials (RMs) for the magnetic properties of hard magnetic materials based on Nd2Fe14B, a highly anisotropic intermetallic compound.Materials and measuring methods Nd-Fe-B permanent magnets were selected as the material for developing the RMs. RM certified values were established using a CYCLE‑3 apparatus included in the GET 198‑2017 State Primary Measurement Standard for units of magnetic loss power, magnetic induction of constant magnetic field in a range from 0.1 to 2.5 T and magnetic flux in a range from 1·10–5 to 3·10–2 Wb.Results and its discussion Based on the experimentally obtained boundary hysteresis loops, the magnetic characteristics were evaluated, the interval of permitted certified values was set, the measurement result uncertainty of certified values was estimated, the RM validity period was established and the first RM batch was released.Conclusion On the basis of conducted studies, the RM type for magnetic properties of NdFeB alloy-based hard magnetic materials was approved (MS NdFeB set). The developed RM set was registered under the numbers GSO 11059–2018 / GSO 11062–2018 in the State RM Register of the Russian Federation.

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Simulating the Hysteretic Characteristics of Hard Magnetic Materials Based on Nd2Fe14B and Ce2Fe14B Intermetallics

Crystals ◽

10.3390/cryst10060518 ◽

2020 ◽

Vol 10 (6) ◽

pp. 518 ◽

Cited By ~ 1

Author(s):

Natalia B. Kolchugina ◽

Mark V. Zheleznyi ◽

Aleksandr G. Savchenko ◽

Vladimir P. Menushenkov ◽

Gennadii S. Burkhanov ◽

...

Keyword(s):

Magnetic Anisotropy ◽

Magnetic Materials ◽

Permanent Magnets ◽

Mixed Valence ◽

Hysteresis Loops ◽

Anisotropy Field ◽

Spin Reorientation ◽

Cost Ratio ◽

Hard Magnetic Materials ◽

Negative Effect

The Ce2Fe14B intermetallic, like Nd2Fe14B, has the tetragonal Nd2Fe14B-type structure (space group P42/mnm), in which Ce ions have a mixed-valence state characterized by the coexistence of trivalent 4f1 and tetravalent 4f0 electron states. Despite the fact that the saturation magnetization, magnetic anisotropy field, and Curie temperature of the Ce2Fe14B intermetallic are substantially lower than those of Nd2Fe14B and Pr2Fe14B, Ce2Fe14B retains the capacity of being able to be used in the manufacturing of rare-earth permanent magnets. Moreover, at low temperatures, the anisotropy field of Се2Fe14B is higher than that of Nd2Fe14B, and Се2Fe14B does not undergo the spin-reorientation transition. In this respect, studies of (Nd, Ce)-Fe-B alloys, which are intended for the improvement of the service characteristics-to-cost ratio, are very relevant. A model and algorithm for calculating the hysteresis loops of uniaxial hard magnetic materials with allowance for the K1 and K2 (K2 > 0 and K1 > 0 and K1 < 0) magnetic anisotropy constants were developed and allowed us to obtain data on their effect on the parameters of hysteresis loops for a wide temperature range (0–300 K). The simulation and analysis of hysteresis loops of the quasi-ternary intermetallics (Nd1−хСех)2Fe14B (х = 0–1) was performed. Results of the simulation indicate that the alloying of the Nd2Fe14B intermetallic with Ce to x = 0.94 (1) does not completely eliminate the negative effect of spin-reorientation phase transition on the residual magnetization of the (Nd1−хCeх)2Fe14B intermetallic and (2) slightly decreases the slope of magnetization reversal curve.

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Micromagnetic Simulations of Fe and Ni Nanodot Arrays Surrounded by Magnetic or Non-Magnetic Matrices

Nanomaterials ◽

10.3390/nano11020349 ◽

2021 ◽

Vol 11 (2) ◽

pp. 349

Author(s):

Devika Sudsom ◽

Andrea Ehrmann

Keyword(s):

Magnetic Materials ◽

Data Storage ◽

Magnetization Reversal ◽

Hysteresis Loops ◽

Object Oriented ◽

Basic Research ◽

Memory Systems ◽

The Other ◽

Micromagnetic Simulations ◽

Nanodot Arrays

Combining clusters of magnetic materials with a matrix of other magnetic materials is very interesting for basic research because new, possibly technologically applicable magnetic properties or magnetization reversal processes may be found. Here we report on different arrays combining iron and nickel, for example, by surrounding circular nanodots of one material with a matrix of the other or by combining iron and nickel nanodots in air. Micromagnetic simulations were performed using the OOMMF (Object Oriented MicroMagnetic Framework). Our results show that magnetization reversal processes are strongly influenced by neighboring nanodots and the magnetic matrix by which the nanodots are surrounded, respectively, which becomes macroscopically visible by several steps along the slopes of the hysteresis loops. Such material combinations allow for preparing quaternary memory systems, and are thus highly relevant for applications in data storage and processing.

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