A Moessbauer spectroscopy study of the magnetic anisotropy of the Sm2-x Yx Fe17 C0.7 interstitials

In order to shed more light on the influence of the Sm concentration on magnetic anisotropy of the Sm 2-x Yx Fe17 Co0.7 interstitials a Moessbauer spectroscopy study at 4.2 K, 77 K, 295 K and 400 K was undertaken. The drastic enhancement of the hyperfine field at the Fe dumbbell sites which reached values between 38 and 40 T for the compositions with x=0.0, 0.2, 0.4 and 0.6 offered the evidence for the presence of the uniaxial anisotropy confirmed for the composition with x=0.2 and x=0.6 by taking spectra of the magnetically oriented absorbers. The results are discussed in terms of the single ion anisotropy model for Sm3+, using values of the first order crystal field parameter gained in previous studies where the interstitial element was nitrogen instead of carbon. (author)