Magnetic phase transitions in FeCrBSi alloys

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