Optical conductivity and magnetic parameters of the intermetallic compounds R2Fe17-xMx (R=Y, Ce, Lu; M=Al, Si)

Optical properties of the intermetallic compounds R2Fe17-xMx (R=Y, Ce, Lu, M=Al, Si, x=0, 1.7) were investigated in the energy range 0.083-5.64 eV. It was shown that the Curie temperature enhancement for substitutional alloys is accompanied by a decrease in the plasma frequency of the conduction electrons, which indicates a decrease in the density of states at the Fermi level N(E-F). This correlation was explained using the spin-fluctuation model of Mohn and Wohlfarth. From the analysis of recent results on the electronic, structural and magnetic properties of the R2Fe17-xMx compounds, a supposition is made about the connection of N(E-t ) with the distance between Fe ions in the 'dumbbell' crystal site. (C) 2001 Elsevier Science BV All rights reserved.