GIANT FORCED-VOLUME AND SATURATION MAGNETOSTRICTIONS OF AMORPHOUS LA(FEXAL1-X)(13) ALLOYS COMPOSED OF ICOSAHEDRAL CLUSTERS

The dependences of saturation magnetostriction lambda(s) and forced-vo lume magnetostriction partial derivative omega/partial derivative H on the concentration and temperature have been investigated for amorphou s La(FexAl1-x)(13) alloys prepared by high-rate Dc sputtering. The mag netic phase diagram obtained from the differential magnetic susceptibi lity dM/dH has been correlated with these magnetostrictions. The spin freezing temperature T-f is drastically decreased but the Curie temper ature T-C is slightly increased on application of a magnetic field. Th e temperature dependences of lambda(s) and partial derivative omega/pa rtial derivative H exhibit a broad peak at the spin freezing temperatu re T-f. The temperature dependence of lambda(s) for the ferromagnetic alloys is explained by the two-ion model, reflecting the peculiar amor phous structure consisting of icosahedral clusters. The peak of partia l derivative omega/partial derivative H at the Curie temperature becom es indistinct with increasing ferromagnetic state in contrast with the peak at the spin freezing temperature. The giant values of partial de rivative omega/partial derivative H and its divergent behaviour at the spin freezing temperature are accounted for by the variable amplitude of the local magnetic moment in the itinerant spin glasses. The signi ficant large partial derivative omega/partial derivative H is connecte d with the pronounced large magnetovolume and magnetoelastic effects s uch as the spontaneous volume magnetostriction omega(s) compressibilit y kappa and high-field susceptibility chi(hf) which bring about variou s Invar anomalies.