MAGNETIZATION AND SPIN CORRELATION OF 2-DIMENSIONAL TRIANGULAR ANTIFERROMAGNET LUFE2O4

Magnetization, neutron diffraction and Mossbauer measurements have been performed on a two dimensional (2D) double-layered triangular antiferromagnet LuFe3+Fe2+O4 single crystal. Two magnetic rods (0, 1, l) and (1/3, 1/3, l) with broad widths across them reveal that 2D magnetic ordering is not of long range and no 3D one occurs down to 4.2 K in contrast to an ordinary magnetic system. Thermoremanent magnetization measurements suggest that the system consists of various size ferrimagnetic clusters. The characteristic profile of l-scan in (0, 1, l) can be realized by taking account of correlation among clusters for intra double-layers and inter double-layers. The temperature variations of intensity in magnetic scattering can be explained qualitatively by assuming unequal exchange interactions among three sublattice.