Artículos de revistas
Magnetoelastic and thermal effects in the BiMn(2)O(5) lattice: A high-resolution x-ray diffraction study
Fecha
2008Registro en:
PHYSICAL REVIEW B, v.77, n.13, 2008
1098-0121
10.1103/PhysRevB.77.134101
Autor
GRANADO, E.
ELEOTERIO, M. S.
GARCIA-FLORES, A. F.
SOUZA, J. A.
GOLOVENCHITS, E. I.
SANINA, V. A.
Institución
Resumen
High-resolution synchrotron x-ray diffraction measurements were performed on single crystalline and powder samples of BiMn(2)O(5). A linear temperature dependence of the unit cell volume was found between T(N)=38 and 100 K, suggesting that a low-energy lattice excitation may be responsible for the lattice expansion in this temperature range. Between T(*)similar to 65 K and T(N), 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 T(N), 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 T(N) and perhaps higher-order terms in the spin Hamiltonian. Polycrystalline samples grown by distinct routes and with nearly homogeneous crystal structure above T(N) presented structural phase coexistence below T(N), indicating a close competition amongst distinct magnetostructural states in this compound.