Ordering in quasi-two-dimensional planar ferromagnets: A neutron scattering study of graphite intercalation compounds

1987 ◽  
Vol 36 (13) ◽  
pp. 7051-7062 ◽  
Author(s):  
D. G. Wiesler ◽  
M. Suzuki ◽  
H. Zabel
1980 ◽  
Vol 2 (1-2) ◽  
pp. 143-148 ◽  
Author(s):  
J. Rossat-Mignod ◽  
D. Fruchart ◽  
M.J. Moran ◽  
J.W. Milliken ◽  
J.E. Fischer

1982 ◽  
Vol 20 ◽  
Author(s):  
M Elahy ◽  
G. Dresselhaus

ABSTRACTPrecise measurements of the temperature dependence of the magnetic susceptibility for stage 2 and 5 graphite-CoCl2 intercalation compounds are reported. Comparison of the experimental results with theoretical calculations based on a two-dimensional planar model show agreement with theory, suggesting that graphite intercalation compounds represent ideal two-dimensional magnetic systems.


1990 ◽  
Vol 5 (2) ◽  
pp. 422-434 ◽  
Author(s):  
Masatsugu Suzuki ◽  
Louis J. Santodonato ◽  
Mildred Yeh ◽  
Samuel M. Sampere ◽  
Andrew V. Smith ◽  
...  

The structural and magnetic properties of the stage 2 CocNi1−cCl2- and COcFe1−cCl2-graphite intercalation compounds (GICs) for 0 ≤ c ≤ 1 have been studied by x-ray scattering and dc magnetic susceptibility. The stage 2 CocNi1−cCl2-GICs approximate two-dimensional randomly-mixed ferromagnets with XY spin symmetry. The average effective magnetic moment Peff, the Curie-Weiss temperature θ, and the paramagnetic-to-ferromagnetic phase transition temperature Tc have been determined as continuously varying functions of Co concentration c. They indicate that the Co2+ and Ni2+ spins are randomly distributed on the triangular lattice sites of each intercalate layer. They also show that the intraplanar exchange interaction J(Co–Ni) between the Co2+ and Ni2+ spins is enhanced and is larger than the interaction J(Co–Co) between two Co2+ spins and J(Ni–Ni) between two Ni2+ spins. This enhanced interaction, J(Co–Ni), can be expressed as J(Co–Ni) = 1.28 [J(Co–Co) · J(Ni–Ni)]1/2. The stage 2 CocFc1−cCl2-GICs approximate two-dimensional randomly mixed ferromagnets with competing spin anisotropy. The dc magnetic susceptibility results suggest that Co2+, Fe3+ rather than Fe2+ are distributed in the intercalate layer. The repeat distance along the c-axis (d-spacing) versus Co concentration deviates from Vegard's law which states that the d-spacing is proportional to Co concentration. The broad peak of d-spacing observed at c = 0.75 is discussed in terms of the double layer model developed by Jin and Mahanti.


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