Magnetic and Neutron Diffraction Studies of the Polycrystalline and Nanoparticle TbMnO3

作者：Bazela W; Dul M; Dyakonov V; Gondek L; Hoser A; Hoffmann J U; Penc B; Szytula A^*; Kravchenko Z; Nosalev I; Zarzycki A

来源：Acta Physica Polonica, A, 2012, 122(2): 384-390.

This paper reports on investigations of magnetic properties, crystal and magnetic structures on TbMnO3 prepared in various ways, namely, as conventional polycrystalline sample and two nano particle specimens (synthesized with a sol gel method at temperatures of 800 and 850 degrees C). The X-ray and neutron diffraction data confirm the orthorhombic crystal structure (space group Pbnm, No. 62) without noticeable differences of the lattice parameters for poly- and nanocompounds. For the polycrystalline sample, a subsequent ordering of the Mn and Tb sublattices with decreasing temperature was observed. Namely, the Mn sublattice exhibits a modulated magnetic structure with the propagation vector k = (0, k(x), 0) in between 41-5 K. Below T = 21 K, a change from a collinear (A(y) mode) into non-collinear (A(y)G(z) mode) structure was evidenced. Further decreasing of temperature below 10 K results in magnetic ordering of the Tb sublattice (modulated G(x)A(y)F(z) mode). For nanoparticle compounds, magnetic ordering in the Mn and Tb sublattices is described by propagation vector k = (0, k(y), 0), with k(y) components higher than observed for polycrystalline sample. The magnetic ordering in the Mn sublattice is described by a collinear A(y) mode down to 1.6 K where the Tb moment becomes ordered (G(x)A(y) mode). The observed broadening of the Bragg peaks connected to the Tb sublattice suggests the cluster-like character of its magnetic structure.

• 出版日期2012-8