Composition and film thickness effects on microstructure and magnetic properties of ordered L10-structured Fe100−xPtx films

Fe100−xPtx films with different Pt atomic fractions (x) and film thicknesses (tf) were fabricated by magnetron sputtering at room temperature and subsequently annealed at 650 °C. Their structure and magnetic properties have been investigated systematically. All the as-deposited Fe100−xPtx films with disordered face-centered-cubic (fcc) structure are soft ferromagnetic. The annealed Fe100−xPtx films evolve from Fe3Pt, FePt to FePt3 with increasing x. High-temperature annealing makes the Fe100−xPtx films transform from the disordered fcc structure to the ordered face-centered-tetragonal (fct) L10 structure as x is in the range of 40-60. The grain size of the annealed Fe52Pt48 films increases with increasing tf. All the annealed Fe100−xPtx films are hard ferromagnetic. The coercivity of the annealed Fe100−xPtx films first increases, and decreases latterly with increasing x. Meanwhile, the coercivity of the annealed Fe52Pt48 films decreases with increasing temperature.