Separation of perpendicular anisotropy components in dc-magnetron sputtered TbFe amorphous films

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Abstract
Different anisotropy components originating from various mechanisms in dc-magnetron sputtered Tb39Fe70 films have been identified. The inverse magnetostrictive anisotropy component was determined by comparing the anisotropy of Tb30Fe70 films when they were removed from their substrates and when they were still attached to their substrates. The single-ion anisotropy component was then derived by subtracting the pair-ordering anisotropy, which was determined as the anisotropy of Gd21Fe79 films which had been removed from their substrates, from the anisotropy of Tb30Fe70 films which had been removed from their substrates. By this method, single-ion and inverse magnetostrictive anisotropies were found to contribute 30–60% and 30–65%, depending on argon sputtering pressure, of the total anisotropy, respectively. Pair-ordering was responsible for less than 10% of the total anisotropy in dc-magnetron sputtered Tb30Fe70 films. Thermal stability of each anisotropy component was studied by annealing films when still attached to their substrates. The anisotropies of films, which had been annealed and removed from their substrates were then compared with those of films, which had also been removed from their substrates but without annealing. Effects of Ar sputtering pressure on the thermal stability of anisotropy were also investigated. Better thermal stability was found in single-ion and pair-ordering anisotropy than in magnetostrictive anisotropy. Films deposited at lower argon pressures show better thermal stability of single-ion and pair-ordering anisotropy than those deposited at higher argon sputtering pressures.