Nanostructure and magnetic properties of composite CoPt:C films for extremely high-density recording

Abstract

The nanostructure and magnetic properties of composite CoPt:C films at room temperature were investigated as a function of annealing temperature, carbon concentration, and film thickness. CoPt:C films with a variety of carbon concentrations were fabricated by cosputtering Co, Pt, and C onto water-cooled Si(100) substrates followed by annealing. X-ray diffraction and transmission electron microscopy analyses indicate that nanocrystallites of face-centered-tetragonal (fct) CoPt phase, which has a uniaxial magnetocrystalline anisotropy constant of about 5×107 erg/cm3, can be formed in carbon matrix when the annealing temperature is higher than 600 °C. The grain sizes of the fct CoPt crystallites are about 10 nm and the coercivities can be as high as 12 kOe. Higher annealing temperature and lower carbon concentration generally lead to larger grain sizes and perhaps more complete formation of the fct CoPt phase, and therefore higher coercivities. The coercivity is insensitive to the film thickness until the thickness is smaller than the CoPt grain size, when the coercivity starts to decrease with film thickness. The magnetic activation volumes are typically around 1×10−18 cm3. The nanostructure and the associated magnetic properties of these composite CoPt:C films are promising as potential media for extremely high-density recording.

Surfactant‐Assisted Synthesis and Characterization of Novel Chain‐Like CoNi Alloy Assemblies

“…Several kinds of magnetic anisotropy can be considered to meet this requirement, including (a) shape anisotropy of elongated magnetic particles, such as rods and wires; [7] (b) magnetocrystalline anisotropy (for example: CoPt, FePt, CuNi, FeNi 3 , etc. ); [8][9][10][11][12] and (c) exchange anisotropy of ferromagnetic/antiferromagnetic core-shell particles. [13] As important transition metal alloys, CoNi alloys have been widely used for decoration, corrosion resistance and magnetic recording devices, etc.…”

Локализованные Моды Спин-Волнового Резонанса Ферромагнитных Микрополосок В Поле Магнитного Зонда

“…Расче-ты проводились для двух различных систем. Пер-вая представляла собой микрополоску из пермаллоя [8,9]. В расчетах параметр диссипации составлял 0.01.…”

Study of the grain growth mechanism of CoPt/Cn thin film for magnetic recording media using the Monte Carlo simulation

“…This film is, however, known to be prone to the occurrence of excessive grain growth during transformation annealing and to high transition noise because of the lack of magnetic granular isolation [1]. To solve this problem, the composite film of L1o granular CoPt particles imbedded in the carbon matrix has been the subject of extensive studies [2,3]. The composite film was fabricated either by co-sputtering Co, Pt, and C [2] or by sputtering in the form of multilayers (CoPt/C) n [3] followed by annealing.…”

“…To solve this problem, the composite film of L1o granular CoPt particles imbedded in the carbon matrix has been the subject of extensive studies [2,3]. The composite film was fabricated either by co-sputtering Co, Pt, and C [2] or by sputtering in the form of multilayers (CoPt/C) n [3] followed by annealing.…”