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CoFeAlSi alloy films are sputtered at room temperature and annealed at various temperatures. X-ray diffraction measurements reveal as-deposited films are amorphous and a nanocrystalline structure is formed after annealing. The coercivity is found to rapidly increase with the annealing temperature, in line with the grown nanocrystalline grain size. The angle dependent magnetic measurements reveal a thermal-induced cubic structural anisotropy develops with the annealing temperature and is superimposed on a growth-induced uniaxial anisotropy with parallel easy axes. Magnetic properties of the alloy are shown to be strongly influenced by the structural change induced by the thermal treatment. The interplay between thermal dependent magnetization and crystallization behavior of the alloy film is revealed by thermomagnetic measurements. A activation barrier of 1.32 eV is determined using the optical reflectance measurements with variable heating rates. [ABSTRACT FROM AUTHOR]

CoFeB alloy material has attracted interest for its wide uses in magnetic memory devices and sensors. We investigate magnetic properties of thick CoFeB films in the thickness range from 10 to 100 nm sandwiched by MgO and Ta layers. Strong in-plane uniaxial magnetic anisotropy is revealed in the as-deposited amorphous films by angular dependent magnetic measurements, and the growth-induced anisotropy is found to strongly depend on the film thickness. A fourfold cubic magnetic anisotropy develops with annealing, as a result of improved crystalline structure in films confirmed by X-ray diffraction measurements. The observed magnetic properties can be explained by the superposition of the uniaxial and additional cubic magnetic anisotropy, tuned by annealing temperature. [ABSTRACT FROM AUTHOR]

Quaternary Co 2 FeAl 0.5 Si 0.5 Heusler alloy thin films have attracted special attention for the application in magnetoelectronic devices. Co 2 FeAl 0.5 Si 0.5 alloy thin films are fabricated by magnetron sputtering at room temperature. The temperature effects on the magnetic, electrical and optical properties in sputtered Co 2 FeAl 0.5 Si 0.5 alloy films are investigated. Thermomagnetic measurements reveal increased magnetization arising from enhanced crystalline ferromagnetic ordering. Anomalous increase in electrical resistivity with temperature is probed in the alloy film, accompanied with significant change in optical reflectance. The large variations in electrical and optical signals in the alloy film can be attributed to the transition of atomic orderings, confirmed by X-ray diffraction measurements. The activation barrier for the transformation of atomic orderings is determined to be 1.22 eV, showing good thermal stability of the Heusler alloy thin film. [ABSTRACT FROM AUTHOR]

A series of amorphous perpendicular TbFeCo films are sputtered using a composite target. The magnetic properties of the TbFeCo films are found to strongly be influenced by sputtering power. The above- RT magnetic compensation point in the films sputtered at high powers is revealed by thermomagnetic measurements. With increasing the power the compensation point shifts considerably towards higher temperature, while only a slight reduction in the Curie temperature occurs. The coercivity is found to initially increase with the power and then falls, which is in accordance with film composition moving from FeCo-rich to Tb-rich side. This can be well explained by the sputtering yield of Tb, which increases faster than FeCo atoms with the power during the sputtering. Our results show a convenient way to adjust the coercivity of the films by modifying the Tb-to-FeCo ratio using the sputtering power. [ABSTRACT FROM AUTHOR]

A series of Co 2 FeAl 0.5 Si 0.5 (CFAS) films sandwiched by Pd and MgO layers are sputtered and subsequently annealed at various temperatures. Perpendicular magnetic anisotropy is shown to build in the structures with CFAS thickness ranging from 3 to 4.25 nm after annealing. The thickness of a magnetic dead layer and the saturation magnetization are shown to increase with the annealing temperature. Perpendicular magnetic anisotropy is determined to be of 1–2 × 10 6 erg/cm 3 . The plot of thickness dependent anisotropy indicates that the perpendicular anisotropy is contributed by the interfacial anisotropy, which is estimated to be 1.03 erg/cm 2 for the structures annealed at 300 °C. The positive contributions to the PMA made by the interfaces of CFAS/MgO and Pd/CFAS are also identified. Our results provide some useful information on the design and integration of CFAS into the next generation of spintronic devices. [ABSTRACT FROM AUTHOR]