EFFECT OF DEPOSITION RATE ON THE ELECTRICAL-RESISTIVITY, COERCIVITY, AND MAGNETOSTRICTION OF PERMALLOY THIN-FILMS

The deposition rate effect on electrical resistivity, coercivity, and magnetostriction of very thin permalloy films (several ten nanometers) are investigated. Permalloy films are deposited by the electron beam method. The deposition rate (R) is 0.2 approximately 4 nm/s, and the vacuum pressure adjusted during deposition is 10(-4) Pa and 10(-6) Pa to compare the atmosphere effect. The substrate temperature is 473 K, and the film thickness is about 50 nm. All the deposited permalloy films are annealed in a hydrogen gas atmosphere to investigate the influence of oxygen on electrical resistivity of the films. Electrical resistivity (rho) increases as R decreases, but magnetoresistivity (DELTA-rho) and coercivity (H(c)) do not depend on R, for the films deposited in a vacuum of 10(-4) Pa. On the other hand, for the films deposited in a vacuum of 10(-6) Pa, rho and DELTA-rho do not depend on R, but H(c) increases as R decreases. The crystalline grain size in the films deposited at 10(-6) Pa increases as R decreases, but this is not found in the films deposited at 10(-4) Pa. It is considered that the increase of H(c) is attributed to the growth of the grain size. Moreover, the oxygen content in the films deposited at 10(-4) Pa tends to increase as R decreases, and the rho in those films is reduced sharply by H-2 annealing. These results indicate that the increase of rho is caused by the increase of the oxygen content, which is included during deposition. In addition, magnetostriction increases as R decreases for films deposited both in 10(-4) Pa and 10(-6) Pa vacuum, because the Fe concentration increases as R decreases.