Sompolinsky irreversibility order parameter in random magnetic-anisotropy Tb{sub {ital x}}Y{sub 1{minus}{ital x}}Al{sub 2} cubic intermetallics
- Magnetismo de Solidos, Departamento de Fisica de Materia Condensada and Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza and Consejo Superior de Investigaciones Cientificas, 50009 Zaragoza (Spain)
The Sompolinsky or irreversibility order parameter {Delta} has been determined for the series of random magnetic anisotropy (RMA) spin glasses (SG{close_quote}s) Tb{sub {ital x}}Y{sub 1{minus}{ital x}}Al{sub 2} ({ital x}=0.10, 0.15, 0.25), from zero-field-cooled (ZFC) and field-cooled (FC) low-field susceptibility measurements, and low-field{endash}low-frequency susceptibility (ac) measurements. A model is presented which, within the mean-field approximation, extends to RMA systems, with ferromagnetic exchange interactions, the dynamical Sompolinsky{close_quote}s model for random exchange SG{close_quote}s. An expression for the low-field susceptibility of RMA SG{close_quote}s, which includes irreversibility effects, is obtained from this model. The thermal dependence of the susceptibilities {chi}{sub ZFC}, {chi}{sub FC}, and {chi}{sub ac} for the above compounds are well reproduced by our model predictions, allowing a separate determination of the RMA crystal field {ital D} and ferromagnetic exchange {ital J} parameters. Our model allows us to correctly explain the thermal dependence of the Sompolinsky order parameter, {Delta}({ital T}), at the SG-ordered regime for the above intermetallics. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 388332
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 17 Vol. 54; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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