Magnetic static and scaling properties of the weak random-axis magnet (Dy sub x Y sub 1 minus x )Al sub 2

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

DOI:https://doi.org/10.1103/PhysRevB.41.9134· OSTI ID:7156171

Gehring, P M; Salamon, M B ^[1]; del Moral, A; Arnaudas, J I ^[2]

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1. Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL (USA) Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL (USA)
2. Magnetismo de Solidos, Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza y Consejo Superior de Investigaciones Cientificas, 50009 Zaragoza (Spain)

The effects of a random component of the magnetocrystalline anisotropy on the magnetic properties and critical behavior of polycrystalline DyAl{sub 2} have been investigated using dc magnetic measurements. Random magnetic anisotropy (RMA) is produced by site-diluting ferromagnetic DyAl{sub 2} with the nonmagnetic, isomorphic intermetallic YAl{sub 2}. Dilution distorts the cubic Laves-phase unit cell because of a slight lattice mismatch thereby lowering the local crystal symmetry in a random fashion. Additional contributions to the RMA come from spin-orbit scattering by the conduction electrons. Hysteresis loops display little remanence and very small coercive fields, suggesting a weak RMA. This is consistent with estimates of the RMA strength {ital D} obtained using an approach of Chudnovsky {ital et} {ital al}. The magnetization at high temperatures ({ital T}{gt}4{ital T}{sub {ital c}}) is well described by a Curie-Weiss law. The paramagnetic Curie temperatures are positive, implying an average ferromagnetic exchange coupling between Dy ions, and increase with {ital x}. The paramagnetic moment shows no evidence of quenching across the series, thus confirming the well-localized nature of the 4{ital f} electronic orbitals. Low-field thermal scans of the bulk dc magnetization show no sign of a spontaneous moment for Dy concentrations 0.10{le}{ital x}{le}0.90, yet a sharp increase in the magnetization occurs at a temperature {ital T}{sub {ital c}} that increases with {ital x}. A ferromagnetic scaling analysis applied to the line of transitions at {ital T}{sub {ital c}} results in a surprisingly good collapse of the magnetization data. By extension of prior theoretical work of Aharony and Pytte, a direct connection can be made between pure and RMA exponents, which gives remarkable agreement with the experimental values.

• OSTI ID: 7156171
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 41:13; ISSN 0163-1829; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
ALUMINIUM ALLOYS
ANISOTROPY
CURIE-WEISS LAW
DYSPROSIUM ALLOYS
MAGNETIC PROPERTIES
MAGNETIZATION
PHYSICAL PROPERTIES
RANDOMNESS
RARE EARTH ALLOYS
SCALING LAWS
TEMPERATURE DEPENDENCE
YTTRIUM ALLOYS