Determination of crystal-field parameters of Sm/sub 2/Fe/sub 17/N/sub 3/ and Sm/sub 2/Fe/sub 17/C/sub 3/

The crystal-field parameters A/sub 20/ and A/sub 40/ were determined from the magnetocrystalline anisotropy constants K/sub 1/ and K/sub 2/ in a linear approximation for Sm/sub 2/Fe/sub 17/Z/sub x/ (Z=N,C) compounds. For the materials investigated, the values of K/sub 1/ and K/sub 2/ in a temperature range from 4.2-533 K have been obtained by a fit of demagnetization curves. The parameters A/sub n0/ are calculated in two ways: (i) from the K/sub i/ at zero temperature and (ii) from the temperature dependence of the K/sub i/. Both methods give equivalent results. The value A/sub 20//spl ap/-400 Ka/sub 0//sup -2/ has been obtained which corresponds to an inverse THOMAS-FERMI screening length q/spl ap/2.3 /spl Aring//sup -1/ calculated within the framework of the screened charge model.