Unexpectedly Large Magnetic Anisotropy of Fe$_{3}$Pt Alloy Thin Films With Various Crystallographycal Orientations

Abstract

The magnetic anisotropy constants of Fe 3 Pt alloy thin films fabricated by e-beam evaporation onto MgO (100), (111), and (110) substrates held at various deposition temperatures were investigated in conjunction with structure. It is observed that the orientation of the Fe 3 Pt alloy thin films depends on the substrate. The magnetic anisotropy constants of each oriented Fe 3 Pt alloy thin films are found to be structure sensitive. The temperature dependence of the magnetic anisotropy constants and magnetization of the Fe 3 Pt alloy thin films were examined. The dependence for Fe 3 Pt alloy thin films between the magnetic anisotropy constants and magnetization is consistent with the theoretical prediction of M 2 for the two-ion model put forward for the case of the Fe 50 Pt 50 alloy.

Structure, Magnetic Properties, and Phase Transformations in Electrodeposited Fe-Rich Fe–Pt Films

“…In addition, the perpendicular anisotropy of as deposited films as well as those annealed at low T is more distinct; Hc is significant in these films up to 350C annealing, with values about 2.5 kOe. Hc decreases when annealing T reaches 400C, in concomitance with an increase in saturation field, a decrease of Ms and the appearance of a new (200) peak.The observation of a phase with perpendicular anisotropy in 75 at.% Fe has been discussed by Suzuki at al, who reported anisotropy constants up to 6x10 6 J/m 3 in a m-DO 19 hexagonal structure15 . The observed structure is metastable and disappears when annealing above 350C; note that this phase is not detected by XRD, suggesting that this phase could be nanocrystalline.The second group of films (69 and 75 at.% Fe) present clearly distinct trends in the magnetic properties; specifically: (i) The decrease in Ms upon annealing is significantly more pronounced; (ii) magnetic hardening in the in-plane direction is not observed; (iii) a new hard phase is observed at low temperature.…”

“…% films yield a phase structure which depends on the growth procedure; specifically, these films form a L1 2 Fe 3 Pt phase when deposited at low temperature and then annealed at 400-700C, while high temperature deposition results in the direct formation of a tetragonal Fe 3 Pt phase 14 . Most intriguing however is the observation by Suzuki of a high magnetic anisotropy (K 1 ~ 6x10 6 J/m 3 ) in hexagonal (space group m-DO 19 ) Fe 3 Pt films obtained by thermal annealing of e-beam evaporated films 15 . Strain effects during growth may be responsible for the selection among the various metastable phases.…”