MAGNETIC AND CRYSTAL-STRUCTURE AND MAGNETOCRYSTALLINE ANISOTROPY OF HEXAGONAL FE60GA40-XASX (X= 6, 23) AND FEGA23SB17 COMPOUNDS

Powder neutron diffraction at 1.5K has been used to investigate the cr ystal and magnetic structure, whilst the Singular Point Detection (SPD ) technique has been used to measure the temperature and composition d ependence of the magnetic anisotropy of Fe60Ga40-xAsx (x = 6, 23) and FeGa23Sb17. The compounds Fe60Ga17As23 and FeGa23Sb17 are isotypic wit h Ni2In (P6(3)/mmc) and Fe60Ga34As6 is a complex modification of this with a doubling of the lattice constant a of the parent Ni2In subcell. The neutron data show that the magnetic structures are planar at 1.5K . Analysis of the SPD signals also indicates a planar anisotropy for a ll compositions at low temperatures. The temperature dependence of the anisotropy field H(A) is very similar for the Ga compounds whilst for the Sb compound a smoother dependence is observed at low temperatures . The anisotropy field increases irrespective of As or Sb substitution . The Curie point, saturation magnetization and anisotropy field can b e simultaneously increased by changing the relative content of non-mag netic ions.