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Magnetic cluster structures in an iron–nickel invar alloy
Author(s) -
Komura S.,
Lippmann G.,
Schmatz W.
Publication year - 1974
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889874009447
Subject(s) - scattering , invar , condensed matter physics , cross section (physics) , radius of gyration , nickel , spin (aerodynamics) , gyration , radius , transverse plane , magnetization , crystal (programming language) , small angle scattering , physics , chemistry , molecular physics , magnetic field , optics , alloy , nuclear magnetic resonance , geometry , quantum mechanics , computer science , engineering , polymer , programming language , mathematics , computer security , organic chemistry , structural engineering , thermodynamics
Small‐angle scattering from an Fe 65 Ni 35 single‐crystal has been measured with the magnetic field applied parallel and perpendicular to the scattering vector κ . Scattering cross sections due to longitudinal and transverse fluctuations have been calculated. The transverse cross section consists mainly of spin‐wave scattering and has a long tail up to κ = 0.2 Å −1 . This suggests that there are spin‐wave modes heavily damped by magnetic inhomogeneities. The longitudinal cross section can be described by a Guinier approximation (dσ/dΩ) 0 exp (−κ 2 R 2 g /3) for the range 0.05 < κ < 0.2 Å −1 . The forward‐scattering cross section ( d σ/dΩ) 0 and the radius of gyration R g obtained from experiment are compared with values calculated from Kachi's model. In this model the magnetization is zero for every cluster of 60 atoms with a concentration of nickel below 29%. The comparison shows that the observed value for R g (= 7.7 Å) is about twice as large as the calculated one. The observed forward scattering ( d σ/ d Ω) 0 has slightly different values for different crystal orientations and is on the average 75% of the calculated value. The agreement is remarkable with regard to the crudeness of the model.