The Effect of Metal-to-Glass Ratio on the Low-Field Microwave Absorption at 9.4 GHz of Glass-Coated CoFeBSi Microwires

We present an investigation of the effects of the variations in the metal-to-glass ratio of Co-rich microwires, on the low field microwave absorption (LFA) at 9.4 GHz. LFA as a function of the DC applied field exhibited a double peak; its separation increased as the metal-to-total diameter ratio, p, decreased (p= metal diameter/total diameter). We show that the magnetic field between the double peak is associated with twice the microwire anisotropy field, H_K, and that the obtained results can be explained in terms of the magnetoelastic dependence of H_K. A decrease in p led to an increase in the stresses, which in turn produced an increase in the total anisotropy field. In contrast, the removal of glass decreased H _K down to values in the 0.9-1.6 Oe range