Effects of Ag buffer layer on the microstructure and magnetic properties of nanocomposite FePt∕Ag multilayer films

Abstract

The face-centered-tetragonal L1 0 FePt films with ͑001͒ preferred orientation has perpendicular coercivity ͑Hc Ќ ͒ of about 2462 Oe that can be achieved by stacking a structure of ͑FePt 4 nm/ Ag 2 nm͒ 5 multilayer films on the 5 nm thick MgO underlayer and annealing at 600°C for 30 min. It is found that both the perpendicular anisotropy and coercivity of ͑FePt 4 nm/ Ag 2 nm͒ 5 multilayer films are enhanced by introducing an Ag buffer layer ͑Ϲ20 nm͒ between the ͑FePt 4 nm/ Ag 2 nm͒ 5 films and the MgO underlayer. When introducing an Ag buffer layer of 20 nm thickness, the Hc Ќ value of the MgO 5 nm/ Ag 20 nm/ ͑FePt 4 nm/ Ag 2 nm͒ 5 multilayer films is observed to increase from 2462 to 4731 Oe, which has significant potential as perpendicular magnetic recording media for high-density recording.

Effect of magnetic field annealing on microstructure and magnetic properties of FePt films

“…In other words, it is essential to attain (0 0 1)-oriented L1 0 FePt films. The most common method to obtain (0 0 1)-oriented L1 0 FePt films is epitaxial or quasi-epitaxial growth [4][5][6][7][8][9][10]. This method has made great progress in fundamental research.…”

“…Under normal growth conditions, the FePt films deposited directly on amorphous substrates tend to possess a (1 1 1) texture because the (1 1 1) plane is a close-packed plane [4,5]. As is well known, the magnetic easy axis (c axis) of (1 1 1) textured L1 0 FePt thin films is tilted $361 away from the films plane [4,5]. However, as perpendicular magnetic recording media, c axis of FePt films should be normal to the films.…”

Effect of Pt underlayer on the coercivity of FePt sputtered film

“…Among the above, the performance for three of them [18][19][20] is similar to our previous data [16]. In this study, we select Pt as the underlayer material for the FePt hard magnetic film.…”

“…Besides the aforementioned underlayers Cu, Ag and CrRu, different metallic underlayers with various CTEs were reported, such as Ti [18], Ag [19] and Ag top layer [20], etc. Among the above, the performance for three of them [18][19][20] is similar to our previous data [16].…”

Microstructure and magnetic properties of Ag/FePt double layer films with different cooling processes

“…During the annealing process, high strain energy is stored in the film, and decreases the energy barrier of phase transformation from fcc disordered phase to fct ordered phase of FePt, thus resulting in an increase in the coercivity. Ag is immiscible with Fe and Pt, so it tends to stay at the grain boundary of FePt and increase the grain boundary energy, which results in the enhancement of the coercivity and changes the preferred orientation of the FePt film [22]. However, if the Ag layer thickness is too thick or too thin, the effect becomes quite weak, this can explain why the perpendicular coer- civity decreased.…”