Electronic Resource
[S.l.]
:
American Institute of Physics (AIP)
Journal of Applied Physics
57 (1985), S. 3244-3246
ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
(Fe1−xCox)7Se8 samples have NiAs-type structures with or without ordered arrangements (3c or 4c) of cation vacancies. With increasing x, the lattice parameter a remains unchanged but c exhibits a fairly large reduction (∼10% by variation of x from 0 to 1). The Curie temperature decreases with increasing x and the ferrimagnetism disappears at x≈0.6. The effective magnetic moments (∼5.5 μB for x≤0.3) evaluated from the high-temperature portion (range of vacancy disorder) of the 1/χ versus temperature curves are close to the value expected on the ionic model. Results show that the magnetic states up to at least x=0.3 are those attained by a simple replacement of magnetic moments of Fe ions by those of Co ions. Samples with x〉0.6 are weakly magnetic. Nearly temperature-independent ac susceptibility at x≈0.7 indicates the absence of localized moments. In this connection, a correlation between lattice parameters and magnetic character is pointed out for 7 : 8 isomorphs of transition element selenides. The easy-axis rotation from in the c plane towards the c axis with lowering temperature occurs in a different way in two superstructures: The easy axis in 4c structures rotates gradually according to temperature change. In 3c structures with x≤0.1, the rotation takes place at some definite temperature (e.g., 165 K for x=0.1). Corresponding torque curves clearly indicate a first order transition. Details of this anisotropy transition are interpreted as a combined effect of the spin-orbit interaction and other additional terms.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.335112
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