Magnetostatic coupling in soft/hard biphase magnetic systems based on amorphous alloys

We report on magnetic bias in biphase systems arising from by dipolarlike interaction. Composites consist of amorphous ribbons and wires prepared by rapid solidification techniques, surrounded by an electroplated layer. Amorphous metallic core is (Co(0.94)Fe(0.06))(72.5)Si(12.5)B(15) with ultrasoft magnetic behavior (coercivity of 10-10(-1) A/m), and the electroplated coating is crystalline Co(85)Ni(15) alloy with harder magnetic character (coercivity of 10(4) A/m. After premagnetizing in a dc saturating field (10(6) A/m), the low-field (+/- 10(3) A/m) hysteresis loops are ascribed to the magnetization process of the soft core and exhibit a typical shift towards the direction of the premagnetizing field. This shift is ascribed to the magnetostatic field generated by uncompensated poles at the edges of the hard layer, which remains close to its remanence state. The influence of the geometry of both phases on magnetostatic energy term allows us to tailor the bias field and susceptibility of the core. These results open other possibilities to use these materials as sensing elements in magnetic sensor. (c) 2007 American Institute of Physics.