Electronic Structure and Maximum Energy Product of MnBi

Metals

Jihoon Park¹  Yang-Ki Hong¹  Jaejin Lee¹  Woncheol Lee¹  Seong-Gon Kim² 

[1]Department of Electrical and Computer Engineering and MINT Center, the University of Alabama, Tuscaloosa, AL 35487, USA

[2] E-Mails:

[3]Department of Physics & Astronomy and Center for Computational Sciences, Mississippi State University, Starkville, MS 39792, USA

[4] E-Mail:

关键词: MnBi;    permanent magnet;    first-principles calculation;    magnetization;    anisotropy constant;    maximum energy product;   

DOI  :  10.3390/met4030455

来源: mdpi

【 摘 要 】

We have performed first-principles calculations to obtain magnetic moment, magnetocrystalline anisotropy energy (MAE), i.e., the magnetic crystalline anisotropy constant (K), and the Curie temperature (T_c) of low temperature phase (LTP) MnBi and also estimated the maximum energy product (BH)_max at elevated temperatures. The full-potential linearized augmented plane wave (FPLAPW) method, based on density functional theory (DFT) within the local spin density approximation (LSDA), was used to calculate the electronic structure of LPM MnBi. The T_c was calculated by the mean field theory. The calculated magnetic moment, MAE, and T_c are 3.63 μ_B/f.u. (formula unit) (79 emu/g or 714 emu/cm³), −0.163 meV/u.c. (or K = −0.275 × 10⁶ J/m³) and 711 K, respectively. The (BH)_max at the elevated temperatures was estimated by combining experimental coercivity (H_ci) and the temperature dependence of magnetization (M_s(T)). The (BH)_max is 17.7 MGOe at 300 K, which is in good agreement with the experimental result for directionally-solidified LTP MnBi (17 MGOe). In addition, a study of electron density maps and the lattice constant c/a ratio dependence of the magnetic moment suggested that doping of a third element into interstitial sites of LTP MnBi can increase the M_s.

【 授权许可】

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© 2014 by the authors; licensee MDPI, Basel, Switzerland.