NANOCRYSTALLINE HIGH COERCIVICY PRCO /CR THIN-FILMS - POTENTIAL HIGH-DENSITY MAGNETIC RECORDING MEDIA/

PrCo thin films with a Cr underlayer (PrCo//Cr) have been prepared by de magnetron sputtering, The as-deposited PrCo films with a Cr underla yer of 80 nm have coercivity values of about 300 to 400 Oe but after a nnealing at 400 degrees C for 20 min a large enhancement in the coerci vity is observed, The coercivity of the PrCo films after annealing at 400 degrees C varies from 2 kOe to as high as 8 kOe depending on the f ilm thickness and deposition conditions. The as-deposited PrCo//Cr fil ms have a mostly amorphous PI Co layer but after annealing at 400 degr ees C the PrCo layer is nearly 100% crystalline with a grain size of a bout 10 nm as revealed by the high resolution TEM micrographs. The coe rcivity of the films depends Strongly on the Ar pressure during sputte ring of the PrCo layer, while the Ar pressure for the Cr underlayer do es not significantly change the coercivity of the films, The Cr underl ayer thickness was varied from 10 to 160 nm and only a slight change i n coercivity was observed, The magnetic switching volume was estimated by the dependence of apparent coercivity on the sweep rate of the mag netic field and also through magnetic viscosity and remanence measurem ents. The measured switching volume is of the order of 1 to 1.5 x 10(- 18) cm(3).