Magnetic properties of ion beam deposited CoCrPt hard bias films for magnetoresistive heads

Ion beam deposition techniques have been employed to prepare Cr/CoCrPt bilayers for hard bias applications in giant/anisotropic magnetoresistive recording heads. The bilayers were deposited at different deposition angles, which is defined as the angle between deposition beam direction and substrate plane. The magnetic properties of CoCrPt films, such as coercivity (H-c), remnant magnetization-thickness product (M (rt)), and coercive squareness (S*) as a function of CoCrPt layer thickness and deposition angle have been studied and correlated to film microstructures. Typical values of H-c, M (rt), and S* for a Cr100 Angstrom/CoCrPt490 Angstrom bilayer deposited at 42 degrees are 1580 Oe, 2.90 memu/cm(2), and 0.90, respectively. The increase in M (rt) with increasing CoCrPt layer thickness at a fixed deposition angle is accompanied by a linear decrease in H-c. We have observed, however, that for the same bilayer geometry both H-c and M (rt) of CoCrPt layer increase with decreasing deposition angle, whereas S* remains almost unchanged. High angle x-ray diffraction measurements indicate that the hexagonal-close-packed (10(1) over bar 0) crystallographic orientation of CoCrPt films is enhanced with decreasing deposition angles. This suggests that the improvement in both M (rt) and H-c for CoCrPt films deposited with decreasing deposition angle results from an enhancement in in-plane c-axis texture, and crystallinity. This could be attributed to an enhancement in in-plane adatom mobility at low deposition angles. (C) 1999 American Institute of Physics. [S0021-8979(99)32808-5].