Structural and magnetic properties of DyFe 12–x Nb x compounds

Abstract

Spin reorientation effects in DyFe12–xNbx compounds with x=0.6, 0.7 and 0.8 have been investigated by ac magnetic susceptibility and 57Fe Mössbauer effect measurements over the temperature range 4.2–300 K. Refinements of the X-ray diffraction patterns show that DyFe12–xNbx compounds crystallize in the ThMn12-type structure and that the Nb atoms occupy the 8i sites. A spin reorientation from easy axis to easy cone at Tsr1, then to easy plane at Tsr2 with decreasing temperature has been detected by ac susceptibility. Both Tsr1 and Tsr2 decrease monotonically with increasing Nb content (from Tsr1 ∼ 236 K for x=0.6 to Tsr1 ∼ 204 K for x=0.8 and from Tsr2 ∼ 154 K for x=0.6 to Tsr2 ∼ 94 K for x=0.8). Analyses of the Mössbauer spectra (4.2–300 K) reveal a discontinuity in the temperature dependences of the hyperfine parameters at Tsr2 for the 8i Fe. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)