Magnetic Properties of Amorphous Co-Zr-Pd and Co-Hf-Pd Films

The magnetic properties of amorphous Co-Zr-Pd and Co-Hf-Pd films produced by sputtering have been investigated. When the Zr or Hf content is fixed, the saturation magnetization Bs Peaks at a low Pd content, then decreases gradually. In films with a low Zr or Hf content, the saturation magnetostriction ¿s rapidly decreases with the addition of Pd. We have found that there is a wide range of compositions with both a high Bs of 15 kG, and a low ¿s of the order of 10^¿7. The amorphous films with ¿s lower than +1×10^¿6 have a high permeability ¿ after annealing in a rotating magnetic field. The crystallization temperature Tx of amorphous CO-Hf-Pd films depends on the Hf content, and the soft magnetic properties are stable up to about 50° C below Tx. Those amorphous Co-Hf-Pd films with a Bs of 15 kG and ¿s of the order of 10^¿7 have been used as the main pole of single-pole type heads in perpendicular magnetic recording, yielding a high reproduced voltage and high overwrite S/N.