Formation of an anisotropy lattice in Co∕Pt multilayers by direct laser interference patterning

Abstract

We report on the use of direct laser interference patterning to form an "anisotropy" lattice in Co/ Pt thin film multilayers. Co/ Pt multilayers have been extensively studied and, for the compositions studied here, are characterized by strong perpendicular magnetic anisotropy in which the magnetic moment is perpendicular to the film plane. In direct laser interference patterning, two-to-four coherent laser beams from a pulsed Nd:YAG laser strike the sample surface simultaneously, and for sufficiently intense beams the sample properties are modified locally where interference maxima occur. Kerr rotation, magnetic force microscopy, and atomic force microscopy measurements after patterning by one pulse from the laser show that the films have a regular array of "dots" with in-plane magnetization in a background matrix of perpendicular magnetization. Such patterning holds promise for the study of model nanoscale magnetic systems.

Polarization patterning by laser-induced phase change in ferroelectric polymer films

“…The film polarization was patterned by two methods, se quential writing with a focused continuous-wave laser beam, and parallel array production by the interference pattern generated from mutually coherent beams from a pulsed laser [4]. Both methods patterned the sample by local heating to depolarize or melt selected areas.…”

“…Typically, the patterning is accomplished by material ablation, for ex ample, to permanently isolate domains in ferromagnetic [1] or make repeating ferroelectric [2,3] device arrays. A less damaging method is to locally heat the film through a phase change, such as the melting point or ferroelec tric Curie temperature [4]. Polarization patterning by la ser-induced phase change has been demonstrated with ferroelectric polymer thin films, but mainly through melting, photochemical alteration, or other irrevers ible alterations [5,6].…”

Irreversible modification of magnetic properties of Pt/Co/Pt ultrathin films by femtosecond laser pulses

“…For low energies of light pulses, the thermally induced changes of the magnetization and magnetic anisotropy are reversible and may trigger a magnetization precession, 14,15 while with higher light intensities, irreversible changes of the structure can be achieved. Employing few-nanosecond laser pulses, a decrease of the magnetic anisotropy in Pt/Co/Pt systems 16,17 was observed; on the contrary, for Au/Co/Au the possibility of creating the out-of-plane magnetization state with semi-continuous laser irradiation was demonstrated. 18 The reported effects of such laser-annealing were consistent with thermal annealing as discussed above.…”

Pulsed Laser Interference Patterning of Metallic Thin Films

“…Nanosecond pulsed laser interference patterning allows preparing microstructured surfaces in a single shot on areas of mm 2 . This has been shown in several publications for direct patterning of surfaces [1][2][3][4][5][6][7][8] or for the generation of surface energy patterns [9]. Nevertheless for a controlled manufacturing process the understanding of the involved mechanims is essential.…”