Heat treatment to control the coercivity of Pt/Co multilayers

We report on controlled changes in the coercivity of sputter deposited Pt/Co multilayer films by thermal treatment under controlled atmospheres. The as-sputtered coercivities of typically 3.3 kOe can be increased to 10.5 kOe by annealing in air, however for coercivities greater than 6 kOe the rectangular ratio of the multilayer decreases with increasing coercivity. The loop shape can be regained and the coercivity decreased by annealing in a H2/N2 atmosphere.