SENSITIVITY ENHANCEMENT OF CO PT SUPERLATTICES THROUGH UNDERLAYER COMPOSITION MODIFICATION/

Co/Pt superlattice films for magneto-optical recording have a relative ly high Curie temperature compared to rare earth-transition metal film s, which has led to criticism of their recording sensitivity at higher disk velocities. We have prepared high-performance Co/Pt disk recordi ng media using (In2O3)(100-x)(SnO2)(x) (ITO) as the underlayer. We hav e observed a two-fold increase in recording sensitivity as x is increa sed from 0 to 75 mol % SnO2. We have correlated measured sensitivity b ehavior with composition-induced changes in the microstructure and ele ctrical resistivity in the ITO underlayer. ITO deposited with low SnO2 content exhibits crystalline microstructure and low electrical resist ivity, whereas ITO deposited with high SnO2 content exhibits amorphous microstructure and high electrical resistivity. The reduction in crys tallinity with increasing SnO2 content is expected to decrease the ITO thermal conductivity, which can explain the increase in recording sen sitivity. Small changes in Co/Pt coercivity as a function of x can eas ily be compensated by adjusting the ITO sputtering pressure. The optim um combination of Co/Pt sensitivity and coercivity can be readily achi eved by controlling the ITO underlayer composition and sputtering pres sure. (C) 1996 American Institute of Physics.