Resumo

ROSALES, I. et al. Refinement of magnetic domains in FeTbGe₂O₇. Rev. mex. fis. [online]. 2015, vol.61, n.6, pp.432-436. ISSN 0035-001X.

Antiferromagnetic polycrystalline FeTbGe₂O₇ compound presents an ordered magnetic phase when its temperature decreases below the Neel temperature T_N = 42 K. By mean of Rietveld refinement of collected neutron diffraction data, the broadened part of the magnetic peaks was modeled in order to analyze the effect of average size of magnetic domains on the evolution of magnetic structure with temperature. The rise of the magnetic structure was found to be sensitive to the shortening of distances along the c-axis between the magnetic atoms located in the bc-sheets of the layered structure. When the magnetic structure is generated, chains along the b-axis of Tb³⁺-Tb³⁺ atoms are antiferromagnetically coupled. At the same time, ferromagnetic coupling along the c-axis between Tb³⁺-Fe³⁺ atoms located in contiguous chains, couples all the chains along a sheet in the layered structure. The three-dimensional magnetic structure is reached by the ferromagnetic coupling between the set of sheets parallel to bc in the layered structure. A correlation between the size ofthe magnetic domain and the reach of the saturation value for the magnetic moment for Fe³⁺ is suggested. The magnetic reflections appear below 42 K and were modelled independently from those reflections coming from the crystal structure ignoring the effect of magnetostriction.

Palavras-chave : Thortveitite; nanophase; antiferromagnetic; neutron diffraction.