Unexpected effect of boron on magnetic properties and structure of amorphous Fe-rich FeSc alloys

Abstract

The magnetic and structural properties of amorphous (Fe_100-xB_x)₉₂Sc₈ alloys have been investigated in detail. Amorphous (Fe_100-xB_x)₉₂Sc₈ alloys were chosen because boron atoms lead to unexpected modifications in the physical properties, whose measurements, analysis, interpretation and modeling is the aim of the present study. Generally, the introduction of boron atoms in crystalline transition metal alloys such as iron-boron results in a reduction in the magnetic hyperfine field, B_hf, and the magnetic moment at low temperatures. The substitution of iron by boron atoms in amorphous (Fe_100-xB_x)₉₂Sc₈ alloys, however, induces a significant increase in the average magnetic hyperfine fields, while causing a reduction in the measured macroscopic magnetic moments. The latest observation of the proportionality between magnetic moment and B_hf suggests a need for a better understanding of this effect. It will be shown that the spins of 3d-electrons are the key factor for the proportionality between internal magnetic hyperfine fields, B_hf, and magnetic moment. The measured magnetic moment, however, is the sum of the spins of 3d-electrons and magnetic moment of sp-electrons. For this reason, the measured magnetic moment and the behavior of the magnetic moment of 3d-electrons are different. The magnetic moment of 3d-electrons and the sp- moments are, however, the key factors for understanding the magnetic properties of the amorphous (Fe_100-xB_x)₉₂Sc₈ alloys. Another study compared the influence of boron on the 3d magnetic Fe-moment and the macroscopic measured magnetic moment of the sample. Why the measured magnetic moment and the behavior of the moment of 3d-electrons are different is discussed. This report, in addition, emphasizes the influence of atomistic short-range order on the magnetic phenomena.