Curie Temperature and Lattice Constant of Evaporated Nickel Films

Film thickness dependence of the Curie temperature of nickel films is investigated under various experimental conditions. The Curie temperature is found to be nearly constant for films of thickness above 50Å, when the films are deposited on sufficiently outgassed substrates and not exposed to the air after deposition. When the films are exposed to the air, a lowering of the Curie temperature occurs for thin films. The lattice constant of these air-exposed films is found to be increased and the largest increase of spacing is 0.7% of the bulk value. Correlation is found between the lattice constant and the Curie temperature.