Effects of Cr substitution on the low temperature magnetization behavior in amorphous Fe68+xCr12-xSi8B12 ribbons

Abstract Amorphous Fe68+xCr12-xSi8B12 alloys (x=0, 2, 4, 6, 8 and 10) were prepared using single wheel melt spinning technique. Magnetic measurements were carried out in the temperature range from 5–300 K and at an external applied field of 30 kOe. The Curie temperature was found to increase by substituting Cr by Fe. The magnetic behavior at low temperature was analyzed using spin wave theory. The low temperature magnetization curve was found to obey Bloch's T3/2 law. Some parameters are extracted like the spin wave stiffness constant (D) and mean square range of exchange interaction for the different compositions. The values of spin waves constant (D) determined were found to increase with substitution the Cr by Fe. The values of the mean square range of exchange interaction were found to be characteristic of amorphous ferromagnets. The local random anisotropy constant KL was derived from the approach of saturation in the magnetization. KL increases as Cr concentration decreases.