Hard-soft magnetic ribbons with biased hysteresis curves

Nanocrystalline ribbons which present biased hysteresis loops have been obtained by annealing the rapidly quenched Co₆₉Si₁₂B₁₂Fe₄Mo₂Ni₁ amorphous alloy. With the adequate annealing conditions, the induced devitrification produces a soft material whose hysteresis loop biasing can be modified by simply applying an intense dc magnetic field at room temperature, with no field cooling. This anomalous magnetic behavior is analyzed in terms of the switching field distributions and related to the structural properties. It is concluded that a low concentration of individual nanoclusters, completely surrounded by the embedding amorphous matrix, rather than large agglomerates, favors the biasing effect preserving the soft magnetic behavior of the material.