Yasuyuki Kusumoto

Thermal stability of Pt/Co multilayered films

The thermal stability of Pt/Co multilayered films with various underlayers has been studied by annealing up to 400 °C. In Pt/Co films sputtered on glass or amorphous AlN underlayers, their coercivity and the squareness of magnetic hysteresis loops are degraded by annealing above 300 °C. In contrast, in films sputtered on ZnO or Pt underlayers, the coercivity is remarkably increased by annealing at 300 °C. The film with the ZnO underlayer shows a hysteresis loop with perfect squareness even after annealing at 400 °C. The results of x‐ray diffraction indicate that the ZnO underlayer not only enhances the fcc Pt/Co(111) orientation but also prevents the decay of the multilayered structure during annealing. The results of laser microannealing using a conventional disk drive system also indicate that the Pt/Co films with ZnO underlayers have superior resistance to laser damage.

Magnetic field modulation recording on Pt/Co magneto-optical disks

Recording properties have been investigated for a magnetooptical disk made of Pt/Co multilayers. The disk exhibits good recording properties for both light intensity modulation and field modulation methods. Reasonable recording properties, namely a carrier-to-noise ratio (CNR) of 46 dB and a block error rate of 1.9%, have been obtained for the field modulation method which seems to satisfy usual standards. However, in the case of low modulation fields, the Pt/Co disk exhibits lower CNR than conventional disks made of rare earth-transition metal amorphous films because of lower recording carrier. >