Monte Carlo analysis for finite-temperature magnetism ofNd2Fe14Bpermanent magnet

2016/06/30 by Yuta Toga, Munehisa Matsumoto, Seiji Miyashita +4 · 1 voice · 2 citations
Materials Science · Physics and Astronomy · #Magnetic Properties and Applications #Magnetic Properties of Alloys #Magnetic properties of thin films

paper · doi:10.1103/physrevb.94.174433

openalex created_date 2016/06/24 · openalex publication_date 2016/11/21 · openalex updated_date 2026/07/28

Abstract

We investigate the effects of magnetic inhomogeneities and thermal fluctuations on the magnetic properties of a rare-earth intermetallic compound, Nd₂Fe₁₄B. The constrained Monte Carlo method is applied to a Nd₂Fe₁₄B bulk system to realize the experimentally observed spin reorientation and magnetic anisotropy constants K_m^A\phantom\rule4pt0ex(m=1,2,4) at finite temperatures. Subsequently, it is found that the temperature dependence of K₁^A deviates from the Callen-Callen law, K₁^A(T)\ensuremath∝M(T)³, even above room temperature, T_R\ensuremath∼300\phantom\rule4pt0exK, when the Fe (Nd) anisotropy terms are removed to leave only the Nd (Fe) anisotropy terms. This is because the exchange couplings between Nd moments and Fe spins are much smaller than those between Fe spins. It is also found that the exponent n in the external magnetic field H_ext response of barrier height F_B=F_B⁰(1\ensuremath-H_ext/H₀)ⁿ is less than 2 in the low-temperature region below T_R, whereas n approaches 2 when T>T_R, indicating the presence of Stoner-Wohlfarth-type magnetization rotation. This reflects the fact that the magnetic anisotropy is mainly governed by the K₁^A term in the T>T_R region.

Citations

• VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data
• A Guide to Monte Carlo Simulations in Statistical Physics

Cited by

• Calculating temperature-dependent properties of Nd2Fe14B permanent magnets by atomistic spin model simulations
• Atomistic spin dynamics with quantum colored noise

Discussions

• Background I was trying to determine the universality class and hopefully find experimental results for the critical exponents for neodymium Nd $_2$ Fe $_{14}$ B permanent magnets. Looking through the [stackexchange, 1 points]

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