SPIN-WAVE EXCITATIONS AND FLUCTUATIONS OF THE EXCHANGE INTERACTION INAMORPHOUS FE1-XZRX ALLOYS

Detailed magnetization measurements were performed on amorphous Fe1-xZ rx alloys with 0.14 less-than-or-equal-to x less-than-or-equal-to 0.48 at temperatures ranging from 4.2 K to the Curie temperature in extern al magnetic field up to 5 T. An analysis of the experimental data reve als that the fluctuations of the exchange integral resulting from the structural disorder give important contribution to the thermal demagne tization and high-field susceptibility of Fe-rich alloys. For Zr-rich alloys the effect of fluctuations of the exchange integral is negligib le and thermal demagnetization is described in terms of spin-wave exci tations. No Stoner single-particle excitations were observed for alloy s with x > 0.14.