The deliberate manipulation of magnetic anisotropy through controlled adjustments to surface and interface morphology has become important due to its potential applications in spintronics and magnetic memory devices. In the present work, oblique angle deposition (OAD) at 65° to the surface normal on a rippled substrate, keeping nanopatterns on the SiO substrate perpendicular to the OAD projection, has been used to induce in-plane uniaxial magnetic anisotropy (UMA) and its thermal stability in cobalt (Co) thin film. Prior to film preparation, the patterned substrate of wavelength 68 ± 4 nm and amplitude 3.4 ± 0.2 nm was prepared separately using a low-energy ion beam erosion (IBE) process. Grazing incidence small-angle X-ray scattering (GISAXS) and magneto-optical Kerr effect (MOKE) techniques have been used for film characterization. While GISAXS provided information about film structure and morphology, MOKE provided information about magnetic properties, thus making it possible to correlate the temperature-dependent evolution of morphology with that of UMA in the film. A clear anisotropy in the growth of Co film is found to result in strong UMA. Unlike previous studies, which typically observe a reduction in UMA strength with thermal annealing, the present work demonstrates a 31 % increase in UMA strength after annealing up to 200 °C, underscoring the importance of oblique angle deposition on nano-rippled substrates for achieving high UMA and ensuring its thermal stability up to moderate temperatures. The appearance of large UMA and its unusual temperature dependence is understood in terms of the shadowing effects and column coalescence, resulting in more robust shape anisotropy. This work provides insights into morphological anisotropy, elucidating the interplay of shadowing effects, shape anisotropy, and dipolar interactions within interacting column and ripple structures. This method gives rise to morphology-induced anisotropy, which can also be applied to other ferromagnetic films to enhance the magnetic anisotropy and ensure thermal stability.

中文翻译：

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纳米图案基底上倾斜沉积的钴膜增强的磁各向异性及其热稳定性


由于磁各向异性在自旋电子学和磁存储器件中的潜在应用，通过控制表面和界面形态的调整来有意操纵磁各向异性变得非常重要。在目前的工作中，在波纹基底上与表面法线成 65° 的斜角沉积 (OAD)，保持 SiO2 基底上的纳米图案垂直于 OAD 投影，已被用于诱导面内单轴磁各向异性 (UMA) 和其在钴（Co）薄膜中的热稳定性。在薄膜制备之前，使用低能离子束腐蚀（IBE）工艺分别制备波长 68 ± 4 nm 和振幅 3.4 ± 0.2 nm 的图案化基板。掠入射小角 X 射线散射 (GISAXS) 和磁光克尔效应 (MOKE) 技术已用于薄膜表征。 GISAXS 提供有关薄膜结构和形态的信息，而 MOKE 提供有关磁特性的信息，从而可以将形态随温度的变化与薄膜中 UMA 的变化联系起来。发现 Co 膜生长过程中的明显各向异性会导致强 UMA。与之前的研究不同，之前的研究通常观察到热退火会导致 UMA 强度降低，而本研究表明，在退火至 200 °C 后，UMA 强度增加了 31%，这强调了在纳米波纹基底上进行斜角沉积对于实现高强度的重要性。 UMA 并确保其在中等温度下的热稳定性。大 UMA 的出现及其不寻常的温度依赖性可以通过阴影效应和柱聚结来理解，从而产生更强大的形状各向异性。 这项工作提供了对形态各向异性的见解，阐明了阴影效应、形状各向异性以及相互作用的柱和波纹结构内的偶极相互作用的相互作用。这种方法产生了形貌诱导的各向异性，也可以应用于其他铁磁薄膜，以增强磁各向异性并确保热稳定性。