Phenomenological study of the amorphous Fe sub 80 B sub 20 ferromagnet with small random anisotropy

Journal Article · Sun Jul 01 04:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.42.898· OSTI ID:6552002

Tejada, J ^[1]; Martinez, B ^[2]; Labarta, A ^[1]; Groessinger, R; Sassik, H ^[3]; Vazquez, M ^[4]; Hernando, A ^[5]

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1. Facultat de Fisica, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona (Spain)
2. Instituto de Ciencia de Materiales, Consejo Superior de Investigaciones Cientificas, Marti i Franques S/N, 08028 Barcelona (Spain)
3. Institut fuer Experimentalphysik, Technische Universitaet, Vienna (Austria)
4. Instituto de Ciencia de Materiales, Consejo Superior de Investigaciones Cientificas, Serano 144, 28006 Madrid (Spain)
5. Laboratorio Salvador Velayos, Renfe I.M, Apartado 155, 28230 Las Rozas, Madrid (Spain)

The magnetic behavior of some amorphous ferromagnets of composition Fe{sub 80{minus}{ital x}R{ital x}}B{sub 20} ({ital R} being a rare-earth element) is investigated as a function of the external applied magnetic field and temperature using dc magnetic measurements. Random magnetic anisotropy is generated by dilution of rare-earth atoms in the Fe{sub 80}B{sub 20} ferromagnetic matrix. Hysteresis curves show a quasireversible behavior with very small coercivity and remanence, suggesting a weak random magnetic anisotropy. In the high-applied-field regime the samples show ferromagnetic saturation, and from the {ital M} values it is possible to conclude that the light rare-earth atoms (Ce, Nd) are ferromagnetically coupled with the iron atoms, whereas the heavy atoms (Gd, Dy) couple ferrimagnetically to the Fe moments. The temperature dependence of the magnetization has also been studied in the conventional spin-wave framework, and the values obtained for the spin-wave stiffness constant {ital D} are close to 100 meV A{sup 2}, which is typical for this kind of material. In the low-applied-field and low-temperature regime a much more complex behavior is observed as a consequence of the competition between local random anisotropy and exchange interactions. The different dependence on {ital T} of the correlation length associated to the local random anisotropy and to the exchange interactions makes possible the existence of different magnetic orderings, but no phase transition is observed between them.

• OSTI ID: 6552002
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 42:1; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
AMORPHOUS STATE
ANISOTROPY
BORON ALLOYS
FERROMAGNETIC MATERIALS
HYSTERESIS
IRON ALLOYS
MAGNETIC FIELDS
MAGNETIC MATERIALS
MAGNETIC PROPERTIES
MATERIALS
PHYSICAL PROPERTIES
RARE EARTH ALLOYS
SPIN WAVES
TEMPERATURE DEPENDENCE