MAGNETIC PHASE-TRANSITIONS IN FECRBSI ALLOYS

We have studied the magnetic phase transitions of semi: iron-rich FeCr SiB alloys in both the amorphous and crystalline states, and have dete rmined the critical exponents gamma(T), gamma(c) and beta(c). We used a vibrating sample magnetometer for the magnetization measurements, a nd Fe-57 Mossbauer spectroscopy to characterize the solid state of the alloys. The maximum values of gamma(T) are higher for the crystallin e than for the amorphous state. For the crystalline alloys, a decrease in the maximum gamma(T) values is observed as the Cr concentration i s increased, which corresponds to a decrease in the mean hyperfine fie ld at the Fe nuclei.