57Fe Mössbauer and magnetic studies of DyFe12−x Ta x compounds

Abstract

Refinements of the X-ray diffraction patterns show that DyFe 12jx Ta x compounds with x = 0.5-0.7 crystallise in the ThMn 12 -type structure and that the Ta atoms occupy the 8i sites. Spin reorientations have been detected by ac magnetic susceptibility for all compounds below room temperature. First the moments shift direction from easy axis to easy cone at T sr1 , then to easy plane at T sr2 . Both T sr1 and T sr2 increase with increasing Ta content up to x = 0.65 before decreasing with further increase in Ta content. Analyses of the Mössbauer spectra indicate that the individual Fe site hyperfine fields derived at 4.5 K for DyFe 11.35 Ta 0.65 are B hf = 37.4 T, 32.2 T and 27.6 T for the 8i, 8j and 8f sites, respectively.