Microstructures and magnetic properties of FePt permanent magnets

Tanaka, Yasuhiro; Kimura, Nobutada; Hara, Kazuhiro; Yasuda, Katsuhiro; Sakurai, Takeshi

doi:10.1016/s0304-8853(97)00019-x

Cited by 82 publications

(36 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…From the equilibrium phase diagram, the ordering temperature of equiatomic FePt alloy is found to be approximately 1300°C 12) . At this temperature, ordering occurs homogeneously with lattice diffusion 13) . On the other hand, at temperatures considerably below the ordering temperature, ordering proceeds with nucleation and growth of L10 domains from A1 (disordered) matrix 14), 15) .…”

Section: Results Results Results Resultsmentioning

confidence: 99%

Low-temperature Ordering in FePt Films Deposited by Gas Flow Sputtering

et al. 2009

View full text Add to dashboard Cite

FePt films were deposited by a low energy sputtering method, i.e., gas flow sputtering, without heating the substrate. The effects of annealing on the L10 order parameter, morphology, and magnetic properties of the films were studied. The order parameter increased significantly after annealing at 413°C; the order parameter of a 76-nm-thick film was found to be 0.84. The coercivity of the film was 15.6 kOe, which was in agreement with the high order parameter. Scanning electron microscopy observations showed that the ordering in the films proceeded with the growth of grains. The XRD pattern of an unannealed thick (950 nm) film showed a 110 superstructure peak. The small grain size in the as-deposited film and the existence of nuclei of the L10 phase may play key roles in inducing the ordering at a relatively low temperature. These factors may promote discontinuous ordering, wherein ordering proceeds with grain boundary diffusion and growth of grains with an L10 structure.

show abstract

Section: Results Results Results Resultsmentioning

confidence: 99%

Low-temperature Ordering in FePt Films Deposited by Gas Flow Sputtering

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Recently, in order to overcome such difficulties, FePt nanoparticles coated with SiO 2 before annealing were prepared to achieve a high degree of L1 0 order [6,[10][11][12][13][14]. FePt nanoparticles prepared by this method have a H c as large as 1.85 T at 300 K [14], of the same order as the value of 3.0 T observed for L1 0 -FePt (001) particulate films [15], and much larger than the bulk value of 0.16 T [16], the thin film value of 0.55 T [4], and the value of 0.75 T for microfabricated FePt (001) dots [17].…”

mentioning

confidence: 99%

Orbital magnetic moment and coercivity ofSiO2-coated FePt nanoparticles studied by x-ray magnetic circular dichroism

et al. 2014

View full text Add to dashboard Cite

We have investigated the spin and orbital magnetic moments of Fe in FePt nanoparticles in the L10-ordered phase coated with SiO2 by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at the Fe L2,3 absorption edges. Using XMCD sum rules, we evaluated the ratio of the orbital magnetic moment (M orb ) to the spin magnetic moment (Mspin) of Fe to be M orb /Mspin = 0.08. This M orb /Mspin value is comparable to the value (0.09) obtained for FePt nanoparticles prepared by gas phase condensation, and is larger than the values (∼0.05) obtained for FePt thin films, indicating a high degree of L10 order. The hysteretic behavior of the FePt component of the magnetization was measured by XMCD. The magnetic coercivity (Hc) was found to be as large as 1.8 T at room temperature, ∼3 times larger than the thin film value and ∼50 times larger than that of the gas phase condensed nanoparticles. The hysteresis curve is well explained by the Stoner-Wohlfarth model for non-interacting single-domain nanoparticles with the Hc distributed from 1 T to 5 T.

show abstract

“…Magnetism in Fe-Pt alloys has attracted considerable interest because of the possibility of fabricating high performance permanent magnets, [1][2][3][4][5][6] resulting from an ordered tetragonal FePt phase (fct 1 -FePt) with a very high magnetic crystalline anisotropy (K ¼ 7 MJm À3 ). 7) Recently, special attention has been paid to Fe-Pt nanocomposite magnets.…”

Section: Introductionmentioning

confidence: 99%

“…2,6,22) The high Pt contents lead to high materials cost. For extension of their applications fields, it is important to reduce Pt content without detriment to good hard magnetic properties.…”

Section: Introductionmentioning

confidence: 99%

Formation, Crystallized Structure and Magnetic Properties of Fe–Pt–B Amorphous Alloys

et al. 2005

View full text Add to dashboard Cite

An amorphous phase was formed for (Fe 0:75 Pt 0:25 ) 100Àx B x (x ¼ 25 and 30) alloys by melt-spinning. Their crystallization temperature were 671 and 667 K, respectively. The amorphous alloys exhibited good soft magnetic properties. The crystallized structure consisted of 1 -FePt (fct), Fe 2 B and -FePt (fcc) phases, and their average grain sizes were about 15 nm after annealing at 785 K for 900 s. The remanence (B r ), reduced remanence (M r =M s ), coercivity (iH c ) and maximum energy product ðBHÞ max were 0.96 T, 0.83, 340 kA/m and 102.2 kJ/m 3 , respectively, for the 25 at%B alloy, and 0.91 T, 0.82, 368 kA/m and 96.5 kJ/m 3 , respectively, for the 30 at%B alloy. The reversible demagnetization loop behavior was also confirmed. Consequently, the good hard magnetic properties are interpreted as resulting from exchange magnetic coupling among nanoscale hard 1 -FePt and soft Fe 2 B and -FePt magnetic phases.

show abstract

Microstructures and magnetic properties of FePt permanent magnets

Cited by 82 publications

References 9 publications

Low-temperature Ordering in FePt Films Deposited by Gas Flow Sputtering

Low-temperature Ordering in FePt Films Deposited by Gas Flow Sputtering

Orbital magnetic moment and coercivity ofSiO2-coated FePt nanoparticles studied by x-ray magnetic circular dichroism

Formation, Crystallized Structure and Magnetic Properties of Fe–Pt–B Amorphous Alloys

Contact Info

Product

Resources

About

Microstructures and magnetic properties of FePt permanent magnets

Cited by 82 publications

References 9 publications

Low-temperature Ordering in FePt Films Deposited by Gas Flow Sputtering

Low-temperature Ordering in FePt Films Deposited by Gas Flow Sputtering

Orbital magnetic moment and coercivity ofSiO2-coated FePt nanoparticles studied by x-ray magnetic circular dichroism

Formation, Crystallized Structure and Magnetic Properties of Fe&ndash;Pt&ndash;B Amorphous Alloys

Contact Info

Product

Resources

About

Formation, Crystallized Structure and Magnetic Properties of Fe–Pt–B Amorphous Alloys