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|Type:||Artigo de periódico|
|Title:||Magnetoelastic And Thermal Effects In The Bi Mn2 O5 Lattice: A High-resolution X-ray Diffraction Study|
|Abstract:||High-resolution synchrotron x-ray diffraction measurements were performed on single crystalline and powder samples of Bi Mn2 O5. A linear temperature dependence of the unit cell volume was found between TN =38 and 100 K, suggesting that a low-energy lattice excitation may be responsible for the lattice expansion in this temperature range. Between T* ∼65 K and TN, all lattice parameters showed incipient magnetoelastic effects, due to short-range spin correlations. An anisotropic strain along the a direction was also observed below T*. Below TN, a relatively large contraction of the a parameter following the square of the average sublattice magnetization of Mn was found, indicating that a second-order spin Hamiltonian accounts for the magnetic interactions along this direction. On the other hand, the more complex behaviors found for b and c suggest additional magnetic transitions below TN and perhaps higher-order terms in the spin Hamiltonian. Polycrystalline samples grown by distinct routes and with nearly homogeneous crystal structure above TN presented structural phase coexistence below TN, indicating a close competition amongst distinct magnetostructural states in this compound. © 2008 The American Physical Society.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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