Analysis of magnetization processes in nanocomposite hard magnetic materials from macroscopic magnetic measurements and X-ray magnetic circular dichroism

摘要

A series of RE{sub}xTM{sub}(bal)B{sub}y (3≤x≤5.5, 15≤y≤25 at.%) nanocomposite magnets were prepared using the classical method of alloy rapid quenching and subsequent devitrification. Appropriate elemental additions and substitutions allowedthe technical magnetic properties to be optimized. The analysis of the both hysteresis cycles and static susceptibility measurements in the range 20 K-300 K reveals that magnetization reversal in these materials can be interpreted schematically as atwo-step process: the initial magnetization reversal is dominated by reversible processes while irreversible processes, which characterize the coercivity mechanism, occur at larger field values. To complement this study, X-Ray Magnetic Circular Dichroism(XMCD) spectroscopy was applied as an element-selective probe of magnetization reversal in nanocomposite samples. This allowed the hysteresis cycles of both hard and soft phases to be separated from the total cycle. Magnetization processes in these bulkheterogeneous systems are discussed in the light of information brought by the complementary applied experimental techniques.