Energy barrier analysis on hot-deformed Nd-Fe-B magnets

R. Goto, S. Okamoto, T. Akiya, N. Kikuchi, O. Kitakami, H. Sepehri-Amin, T. Ohkubo, K. Hono, K. Hioki, A. Hattori

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

One approach to solve the so-called coercivity problem on Nd-Fe-B permanent magnet is to investigate the magnetization reversal process. The magnetization reversal is a transition event between two energy local minima separated by an energy barrier. The energy barrier Eb is a function of magnetic field H and is generally given as the form of Eb = E0(1 - H/H0)n, where E0 is the barrier height at zero magnetic field, H0 the intrinsic coercivity without thermal fluctuation, n the constant. These parameters strongly depend on the magnetization reversal process, but the experimental determination of n is somewhat difficult. Recently, we have proposed the novel experimental method to determine the value of n based on the magnetic viscosity measurements [1]. The parameters of E0, H0 and n also depend on the field direction with respect to the magnetic easy axis. Thus using a highly oriented sample is indispensable for this analysis. A newly developed hot-deformed Nd-Fe-B magnet with Nd-Cu eutectic diffusion under expansion constraint is a good sample for this analysis, because it exhibits very high coercivity of about 20 kOe and excellent c-axis orientation [2]. In this study, energy barrier of the hot-deformed Nd-Fe-B magnets with and without Nd-Cu diffusion are analyzed and the magnetization reversal process and the temperature dependent coercivity are discussed.

Original languageEnglish
Title of host publication2015 IEEE International Magnetics Conference, INTERMAG 2015
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Electronic)9781479973224
DOIs
Publication statusPublished - 2015 Jul 14
Event2015 IEEE International Magnetics Conference, INTERMAG 2015 - Beijing, China
Duration: 2015 May 112015 May 15

Publication series

Name2015 IEEE International Magnetics Conference, INTERMAG 2015

Other

Other2015 IEEE International Magnetics Conference, INTERMAG 2015
Country/TerritoryChina
CityBeijing
Period15/5/1115/5/15

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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