Structural transition from L1 phase to A1 phase in FePt films caused by ion irradiation

Abstract

Structure and magnetic properties of FePt(001) graded films deposited on glass substrates Domain wall assisted magnetization switching in (111) oriented L 1 0 FePt grown on a soft magnetic metallic glass Appl. Phys. Lett. 97, 072510 (2010); 10.1063/1.3479054 Phenomenological analysis of magnetization reversal process for L 1 0 -Fe Pt ( 001 ) particulate filmsThe effect of ion irradiation ͑B + ,Cr + ,Ga + , and Nb + ͒ on the crystalline structure and magnetic properties of L1 0 ͑face-centered tetragonal structure͒ FePt films was investigated. Irradiating with Cr + , Ga + , and Nb + ions of less than 1 at. % ͑1.6ϫ 10 15 ions/ cm 2 ͒ dose yielded an almost ideal structural transition from the L1 0 to A1 ͑face-centered cubic structure͒ phase withoutdamage to the surface of the film. This structural transition was accompanied by a change in magnetic properties from a hard magnet with a coercivity H c of ϳ7 kOe to a soft magnet with H c Ͻ 1 kOe. A two-dimensional pattern composed of hard magnetic L1 0 and soft magnetic A1 phases was fabricated by using a focused Ga + ion beam.

Magnetic patterning by means of ion irradiation and implantation

“…The direct exchange coupling type is mostly studied for the L1 0 -ordered Fe 50 Pt 50 alloy [6][7][8][9][10], where a modification of the direct exchange coupling leads to a modification of the magnetic anisotropy. Ravelosona et al [6] have shown that light ion irradiation of the initially disordered Fe 50 Pt 50 alloy can significantly enhance the degree of L1 0 -ordering without increasing the sample temperature.…”

Structural Dependent Ferromagnetic-Nonmagnetic Phase Change in FePtRu Films

“…Finally, we propose a nanopatterning method for this material system. According to our previous results, the ordered 1 0 structures of FePtX were easily transformed to the disordered 1 structure under ion irradiation [15][16][17][18][19][20][21]. Figure 5 shows the schematics of a nanopatterning method using an FM-PM phase change due to the 1 0 -1 structural transformation caused by ion irradiation.…”

“…[12][13][14], which leads to excellent thermal stability of magnetization in nanometer-size structures. After ion irradiation, the ordered 1 0 FePt films undergo transformation from the hard-FM phase (high ) to the soft-FM phase (low ) with the disordered 1 structure (fcc, = = ) [15][16][17][18][19][20]. Although the 1 0 FePt is suitable for BPM, modifying its properties using ion irradiation is difficult due to the insensitivity of magnetization with ion irradiation.…”

Arrays of Metal Nanostructures Produced by Focussed Ion Beam

“…FePt and CoPt films have been found to have a better or a worse chemical order, and thus a higher [23][24][25] or a lower magnetic anisotropy [26], after the irradiation with light ions (He + and B + ) depending on the used dose. The production of magnetic patterns on continuous magnetic films without significant modification of the surface roughness or of the film optical indices has been demonstrated by parallel irradiation through lithographically patterned stencil masks [19], but the results have also been reported by localized delivery of the damage, using FIB facilities [10,27,28].…”