The magnetic properties and effective magnetic anisotropy of Fe-Ni ultrafine particles

Abstract

Fea00 -~Nix alloys of ultrafine particle with the average grain size of about 10 nm were synthesized by mechanically alloying process. The samples were investigated by X-ray diffraction and measurements of the saturation magnetization and coercivity force. Both b. c. c and f. c. c phase exist within a wide range for Fel00 -~ Ni~, while x~45. The effective magnetic anisotropy K e was measured by applying the law of approach to saturation. The value of K e decreases with an increase of Ni content. It is noticed that the strain anisotropy makes a large contribution to the magnetic anisotropy. The estimation of grain size leads to the determination of the single domain critical size and domain wall energy. The exchange stiffness and exchange integral deduced from the relationship between the effective magnetic anisotropy and domain wall energy are in agreement with that calculated by other methods.

Partial band gaps in magnonic crystals

“…Furthermore, A A ¼ 2:88Â10 À11 J/ m for Co, and A B ¼ 1:11 Â10 À11 J/m for Py. 13 We define the exchange term in the interface A/B to be…”

Band gaps in the terahertz frequency range in quasiperiodic one-dimensional magnonic crystals

“…The physical parameters used are n A = n B = 4, S A = 5/2, S B = 3/2, and the lattice constant a = 2.5 nm. Furthermore, A A = 2.88 × 10 −11 J/m for Co, and A B = 1.11 × 10 −11 J/m for Py [23]. We define the exchange term in the interface A/B to be I = (J A + J B )/2.…”