Influences of post-annealing and internal stress on magnetoresistance properties of Ni80Fe20 films
(Department of Physics, University of Science and Technology Beijing,
Beijing 100083, China)
Beijing 100083, China)
Abstract: Ni80Fe20 films with thickness about 54nm were deposited on K9 glass and thermally oxidized silicon substrates at ambient temperature by electron beam evaporation with deposition rate about 1.8nm/min. The as-deposited films were annealed at 350, 450 and 570℃ respectively for 1h. After annealing at 570℃, the anisotropic magnetoresistance ratio(RAM) of the films is greatly improved. It increases to 3%-3.5% nearly about three times of that of the as-deposited films. The grain size increases with the annealing temperature and the ［111］ crystal orientation is obviously enhanced after annealing at temperature above 450℃. The internal stress in the films deposited on K9 glass is compressive and the resistance measurement shows that RM∥ is larger than RM⊥ in these films. However, in the films deposited at the same conditions but on oxidized silicon substrates, the internal stress is tensile and RM⊥ is larger than RM∥. The differences of RM∥ and RM⊥ in two series of specimens are discussed.
Key words: Ni80Fe20 film; annealing; internal stress; anisotropic magnetoresistance