Noise reduction mechanisms in laminated antiferromagnetically coupled recording media

Experimental methods to obtain remnant moment-thickness product (M(r)delta) reduction in the laminated antiferromagnetically coupled (LAC) recording m edia is described. The results indicate that the reduction in M(r)delta (or , indirectly, a reduction in noise) can be obtained by altering the antifer romagnetic coupling constant J, or by the parameters of the underlayer such as anisotropy constant (K-u2), thickness (t(2)), etc. A method to enhance J by intrinsic means is proposed by which a high exchange field of about 19 00 Oe can be obtained. Thermal energy has been found to help in obtaining a M(r)delta reduction in LAC media. Substrates with lower surface roughness also enhance the M(r)delta reduction. (C) 2001 American Institute of Physic s.