Ya Huang

Magnetic, thermal, electrical properties and crystallization kinetics of Co60Fe20B20 alloy films

Magnetic, thermal and electrical properties of sputtered Co60Fe20B20 alloy films are investigated. An excellent linear relationship between the saturation magnetization per unit area and thickness is obtained in the as-deposited film with thickness ranging from 10 to 100 nm. For the as-deposited films a high effective saturation magnetization of 793.7 ± 42.9 emu cm-3 is derived from the fitting. An in-plane uniaxial magnetic anisotropy of ~104 erg cm-3 in magnitude is revealed by angular dependent magnetic measurements. A fourfold cubic magnetic anisotropy is found to develop with annealing, in line with the improvement of the crystalline structure in the film confirmed by X-ray diffraction measurements. Thermomagnetic measurements reveal a considerable variation of the saturation magnetization with temperature arising from the competition of the crystallization and the temperature dependent ferromagnetic behavior of the alloy film. Pronounced changes in electrical resistivity with temperature were observed in the alloy film, in accompany with the structural change. The activation barrier for crystallization was determined to be 1.43 eV from the electrical measurements with variable heating rates, showing a good thermal stability of the alloy film.摘要本文研究了溅射制备的三明治结构Ta/Co60Fe20B20/MgO合金薄膜的磁、热、电及晶化动力学特性. 10–100 nm厚度的沉积态合金薄 膜单位面积磁化强度和厚度呈现了极好的线性相关性, 由此拟合出沉积态合金薄膜有效饱和磁化强度高达793.7 emu cm−3. 转角磁测量揭示了沉积态的合金薄膜具有面内磁单轴各向异性, 其大小为104 erg cm−3数量级. 发现4重对称的立方结构磁各向异性随着退火温度升高而 增大, 这与XRD衍射测量的样品结构的变化一致. 热磁曲线揭示了合金薄膜随温度有相当大变动的饱和磁化强度, 这来源于合金晶化与温 度相关的铁磁行为的竞争作用. 伴随结构变化, 观察到明显的合金薄膜电阻随温度的变化. 通过变速率加热电阻测量得到晶化激活能为 1.43 eV, 表明该合金材料具有很好的热稳定性.

Magnetic, thermal, electrical properties and crystallization kinetics of Co60Fe20B20 alloy films@@@Co60Fe20B20合金薄膜磁、热、电特性及晶化动力学研究

Magnetic, thermal and electrical properties of sputtered Co60Fe20B20 alloy films are investigated. An excellent linear relationship between the saturation magnetization per unit area and thickness is obtained in the as-deposited film with thickness ranging from 10 to 100 nm. For the as-deposited films a high effective saturation magnetization of 793.7 ± 42.9 emu cm-3 is derived from the fitting. An in-plane uniaxial magnetic anisotropy of ~104 erg cm-3 in magnitude is revealed by angular dependent magnetic measurements. A fourfold cubic magnetic anisotropy is found to develop with annealing, in line with the improvement of the crystalline structure in the film confirmed by X-ray diffraction measurements. Thermomagnetic measurements reveal a considerable variation of the saturation magnetization with temperature arising from the competition of the crystallization and the temperature dependent ferromagnetic behavior of the alloy film. Pronounced changes in electrical resistivity with temperature were observed in the alloy film, in accompany with the structural change. The activation barrier for crystallization was determined to be 1.43 eV from the electrical measurements with variable heating rates, showing a good thermal stability of the alloy film.摘要本文研究了溅射制备的三明治结构Ta/Co60Fe20B20/MgO合金薄膜的磁、热、电及晶化动力学特性. 10–100 nm厚度的沉积态合金薄 膜单位面积磁化强度和厚度呈现了极好的线性相关性, 由此拟合出沉积态合金薄膜有效饱和磁化强度高达793.7 emu cm−3. 转角磁测量揭示了沉积态的合金薄膜具有面内磁单轴各向异性, 其大小为104 erg cm−3数量级. 发现4重对称的立方结构磁各向异性随着退火温度升高而 增大, 这与XRD衍射测量的样品结构的变化一致. 热磁曲线揭示了合金薄膜随温度有相当大变动的饱和磁化强度, 这来源于合金晶化与温 度相关的铁磁行为的竞争作用. 伴随结构变化, 观察到明显的合金薄膜电阻随温度的变化. 通过变速率加热电阻测量得到晶化激活能为 1.43 eV, 表明该合金材料具有很好的热稳定性.

Investigation of temperature dependent magnetic properties in irradiated Co/Pt multilayer devices using Extraordinary Hall effect measurements

This article reports the experimental results using Ga ion FIB to irradiate Hall devices based on ultrathin Co/Pt multilayers. The multilayers are deposited on Si/SiO2 substrate using DC magnetron sputtering. Temperature dependent magnetic properties of the irradiated devices are investigated by extraordinary Hall effect measurements. The perpendicular magnetic anisotropy in the multilayer is confirmed by polar magneto-optical Kerr effect measurements. Pronounced differences in magnetic reversal of the irradiated devices are observed.