Neutron and X-ray diffraction studies were carried out on polycrystalline specimens of stoichiometric (S-) and non-stoichiometric (N-) YFe 2O4. An asymmetric diffraction line was observed above the Neel point (TN≃235 K) in S-YFe2O4 and both above and below TN (TN≃210 K) in N-YFe 2O4. At above TN, the line profile was quantitatively interpreted as due to two-dimensional critical scattering, on an assumption that the scattering cross section is a Lorentzian in a h-k plane, independent of /. The correlation length, k, and the susceptibility at (1/3, 1/3, /), χ, obey an exponential law: k∝(T-T′n) v and χ∝T-T′n)-y, respectively, with v=1.5±0.05, γ=3.1±0.1 and T′N=233.0= ′=0.5 K in S-YFe2O4. It was concluded that the spin correlation is two-dimensional in the hexagonal YFe2O4, both in the S- and N-compounds, but a crystal deformation induces a three-dimensional spin ordering in S-YFe2O4.
|Number of pages||9|
|Journal||journal of the physical society of japan|
|Publication status||Published - Aug 1984|
ASJC Scopus subject areas
- Physics and Astronomy(all)