L1 ordered phase formation in FePt, FePd, CoPt, and CoPd alloy thin films epitaxially grown on MgO(001) single-crystal substrates

Abstract

The FePt, FePd, CoPt, and CoPd epitaxial thin films are prepared on MgO(001) single-crystal substrates by ultrahigh vacuum RF magnetron sputtering. The effects of the magnetic material and the substrate temperature on the film growth, the film structure, and the magnetic properties are investigated. The L10 ordered phase formation is observed for FePt, FePd, and CoPt films prepared at temperatures higher than 200, 400, and 600 °C, respectively, whereas that is not recognized for CoPd films. The L10-FePd(001) single-crystal films with the c-axis normal to the substrate surface are formed, whereas the FePt and CoPt epitaxial films include L10(100) crystals whose c-axis is parallel to the substrate surface, in addition to the L10(001) crystals. Upon increasing the substrate temperature, the ordering degree increases. A higher ordering parameter is observed in the order of FePd > FePt > CoPt. The magnetic properties are influenced by the crystal structure, the crystallographic orientation of the L10 crystal, and the ordering degree.

Magneto-optical study of anomalous magnetization reversal in the presence of anisotropy dispersion in CoPd thin films

“…It is seen that, because of the smaller atomic radius of Co relative to Pd, the lattice parameter of the film decreases with increasing the Co:Pd ratio. We note that an ordered L1 0 structure is only observed for FePd, FePt, and CoPt thin films, and is not formed in CoPd film, even for the equiatomic Co 50 Pd 50 alloy [19].…”

“…Magnetic anisotropy is one of the most important parameters of magnetic thin films in practical applications [14][15][16]. Among magnetic materials, binary alloys of transition metals including FePt, FePd, CoPt, and CoPd have attracted enormous interest mostly because of their high magnetocrystalline anisotropy energy [17][18][19].…”

Formation of L10-ordered CoPt during interdiffusion of electron-beam-deposited Pt/Co bilayer thin films on Si/SiO2 substrates by rapid thermal annealing

“…Ordered CoPt alloys, especially those containing the L1 0 phase, are the promissing candidates for the nextgeneration ferromagnetic materials because of their strong perpendicular magnetocrystalline anisotropy (PMA) and large coercivity (H c ), which are attributed to a phase transformation from A1-disordered CoPt induced by thermal annealing [1][2][3]. These materials are typically prepared on single-crystal insulating substrates such as MgO(001) [4][5][6][7][8][9][10], Al 2 O 3 (0001) [5,11], and SrTiO 3 (001) [12] to control their crystal orientations and easy axis of magnetization along the perpendicular direction for device applications such as high-density magnetic recording media and magnetic tunnel junctions [13][14][15][16][17][18][19].…”

Thermal stability of L10-FePt nanodots patterned by self-assembled block copolymer lithography

“…For example in heat assisted magnetic recording [6,7], local heating of a region of a high anisotropy magnetic recording medium lowers the energy barrier to the point that the field of the write head is capable of writing data on the medium. This enables the use of hard magnetic materials such as CoCrPt, FePt, CoPt, or FePd [5][6][7][8][9][10][11] for recording media which can have coercive fields over μ 0 H c =3 T after patterning, above the maximum field of ∼2.4 T that a write head can apply.…”