CoPt–Al2O3 Nanocomposite Films: Synthesis, Structure, and Magnetic Properties

Abstract

Представлены результаты исследования структурных и магнитных свойств нанокомпозитных пленок CoPt-Al 2 O 3 , полученных путем отжига двухслойных пленок Al/(Co 3 O 4 + Pt) на подложке MgO(001) при температуре 650°С в вакууме. Синтезированные композитные пленки содержали ферромагнитные наногранулы CoPt со средним размером 25-45 нм, вложенные в непроводящую матрицу Al 2 O 3 . Намагниченность насыщения M s ~ 330 Гс и коэрцитивная сила H c ≈ 6 кЭ измерены в плоскости пленки и перпендикулярно ей. Полученные пленки обладали пространственной магнитной вращающейся анизотропией, позволяющей произвольно устанавливать легкую ось намагничивания, как в плоскости пленки, так и перпендикулярно ей, в магнитном поле напряженностью, превышающей коэрцитивную силу (H > H c ).

Homogenization and short-range chemical ordering of Co–Pt alloys driven by the grain boundary migration mechanism

“…Typically, in binary intermetallic large coercive fields are achieved in chemically ordered phases of the alloy possessing a strong magnetic anisotropy [6][7][8][9]. Therefore, the formation of chemically ordered highly anisotropic CoPt phases is intensively investigated in both thin films and nanoparticles relying on doping of CoPt alloys with additional elements [10][11][12][13][14], growth at elevated temperatures [15][16][17][18][19][20][21], realization of composite materials [22] and ion beam irradiation [23,24]. Post-thermal treatment [25][26][27][28], e.g.…”

Magnetic and Structure Properties of CoPt-In₂O₃ Nanocomposite Films

“…1 shows the scheme for synthesizing CoPt-In 2 O 3 nanocomposite films. First, we prepared the CoPt(111) ferromagnetic films using the technique described in [20]. This began with the magnetron sputtering of Pt films with a thickness of ∼ 50 nm in a vacuum at a residual pressure of 10 −6 Torr onto a MgO(001) substrate heated to a temperature of ∼ 250 • C, which ensured epitaxial growth of the Pt(111) plane relative to the substrate surface.…”

“…Next was the thermal deposition of a polycrystalline Co film with a thickness of ∼ 70 nm in a vacuum at a residual pressure of 10 −6 Torr onto the Pt film at room temperature to prevent a reaction between the layers (the chosen thicknesses of the reacting layers were ∼70 nm for Co and ∼ 50 nm for Pt, which provided an equiatomic composition), followed by the annealing of the obtained Co/Pt(111)/MgO bilayer samples in a vacuum at 10 −6 Torr at a temperature of 650 • C for 90 min. After annealing the Co/Pt(111)/MgO samples, the magnetically hard L1 0 -CoPt(111) phase forms in the Co/Pt(111) film structure based on the oriented Pt(111) layer [20,27]. The thicknesses of the reacting layers were determined by X-ray fluorescence analysis.…”

“…CoPt and FePt alloy films have attracted a great deal of attention because of their strong perpendicular magnetic anisotropy, which is important for many practical applications. To date, there have been a small number of studies on the synthesis and investigation of nanocomposites containing CoPt and FePt nanoparticles in oxide matrices [20][21][22][23][24][25][26]. These investigations are important for applications involving the synthesis of nanocomposites with the desired magnetic, structural, and transport properties.…”