Abstract
The powder alignment method is used to investigate the anisotropic physical properties of the weak-ferromagnetic superconductor system RuSr 2 RCu 2 O 8 (R Pr, Nd, Sm, Eu, Gd, Gd 0.5 Dy 0.5 ). Due to weak magnetic anisotropy of this tetragonal system, partially c-axis aligned microcrystalline powder (diameter ∼ 1-10 μm) in epoxy can be obtained only for R Eu and Gd through the field-rotation powder alignment method where c-axis is perpendicular to the aligned magnetic field B a 0.9 T and parallel to the rotation axis. For smaller rare earth compound R Gd 0.5 Dy 0.5 , powder alignment can be achieved using the simple field powder alignment method where c-axis is partially aligned along the aligned magnetic field. No powder alignment can be achieved for larger rare earths R Pr, Nd or Sm due to the lack of magnetic anisotropy in these compounds. The mechanism of powder alignment at room temperature using the spin-orbital-related anisotropic paramagnetic susceptibility and the low temperature anisotropic physical properties of RuSr 2 EuCu 2 O 8 is discussed. © 2009 IOP Publishing Ltd.