Low temperature magnetostriction of amorphous Fe₈₅B₁₅ ribbons

Abstract
In this work we present measurements of the low temperature behavior of the magnetostriction of amorphous Fe₈₅B₁₅ samples that were produced by planar flow casting. For these low temperature measurements we developed a new system in order to characterize amorphous or nanocrystalline ribbons in a temperature range between 2 K and 300 K. With the system the low temperature dependence of magnetostriction can be measured by the SAMR (Small Angle Magnetization Rotation) method which exhibits a high sensitivity. Additionally magnetic measurements like hysteresis loop, initial susceptibility and pinning field were performed with the same equipment simultaneously on the same piece of ribbon. The magnetostriction and the magnetization data of the Fe₈₅B₁₅ sample were used for analyzing the temperature dependence of magnetostriction in the low temperature range. From scaling laws between the magnetostriction and the saturation magnetization information about the physical mechanism of magnetostriction can be obtained. The temperature dependence of coercivity H_c will also be analyzed by various models. From the temperature dependence of the magnetization, which follows the Bloch T_3/2 law, the spin wave stiffness constant can be estimated.