Anisotropy of exchange stiffness based on atomic-scale magnetic properties in the rare-earth permanent magnet Nd2Fe14B
| Autor: | Takashi Miyake, Akimasa Sakuma, Seiji Miyashita, Masamichi Nishino, Yuta Toga |
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| Rok vydání: | 2018 |
| Předmět: |
Physics
Condensed matter physics 02 engineering and technology Coercivity 021001 nanoscience & nanotechnology 01 natural sciences Atomic units Orientation (vector space) Crystal Ab initio quantum chemistry methods 0103 physical sciences Spin model 010306 general physics 0210 nano-technology Anisotropy Micromagnetics |
| Zdroj: | Physical Review B. 98 |
| ISSN: | 2469-9969 2469-9950 |
| DOI: | 10.1103/physrevb.98.054418 |
| Popis: | We examine the anisotropic properties of the exchange stiffness constant $\mathcal{A}$ for a rare-earth permanent magnet, ${\mathrm{Nd}}_{2}{\mathrm{Fe}}_{14}\mathrm{B}$, by connecting analyses with two different scales of length, i.e., Monte Carlo (MC) method with an atomistic spin model and Landau-Lifshitz-Gilbert (LLG) equation with a continuous magnetic model. The atomistic MC simulations are performed on the spin model of ${\mathrm{Nd}}_{2}{\mathrm{Fe}}_{14}\mathrm{B}$ constructed from ab initio calculations, and the LLG micromagnetics simulations are performed with the parameters obtained by the MC simulations. We clarify that the amplitude and the thermal property of $\mathcal{A}$ depend on the orientation in the crystal, which are attributed to the layered structure of Nd atoms and weak exchange couplings between Nd and Fe atoms. We also confirm that the anisotropy of $\mathcal{A}$ significantly affects the threshold field for the magnetization reversal (coercivity) given by the depinning process. |
| Databáze: | OpenAIRE |
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