Khanduri H, Dimri Mukesh C, Kumar Prashant, Chaudhary Shanu, Anand Kritika, Pant R P
Indian Reference Materials, CSIR-National Physical Laboratory New Delhi-110012 India
Jaypee University Anoopshahr UP-203390 India.
RSC Adv. 2019 Dec 17;9(71):41764-41774. doi: 10.1039/c9ra09272b. eCollection 2019 Dec 13.
Ferromagnetism and magnetic anisotropy in Mn-Al thin films can be of great interest due to their applications in spintronic components and as rare-earth free magnets. Temperature-dependent uniaxial anisotropy has been observed in ferromagnetic MnAl thin films, which is attributed to the modification of the tetragonal lattice distortion with the change in annealing temperature, confirmed by VSM, MOKE and XRD results; the annealing time did not affect the magnetic anisotropy. A simple evaporation technique was used to deposit the Mn/Al bilayer thin films (thickness ∼ 64 nm) on GaAs substrates. A comprehensive study of the effect of annealing temperature as well as annealing time on structural, microstructural, magnetic and magneto-optical properties are reported in this paper. The ferromagnetic phase was enriched in annealed samples, which was confirmed by XRD, MOKE and magnetic hysteresis loops. XRD results revealed that the ferromagnetic τ-phase was enhanced in annealed films with the increase in annealing temperature ≥ 400 °C. Surface roughness was estimated from the AFM micrographs and was found to be increased, whereas the mean grain size was decreased on annealing the as-deposited Mn/Al bilayer thin film. The gradual increase in magnetic coercivity was found on increasing the annealing temperature. It is interesting to note that the magnetic easy axis can be tuned by changing the annealing temperature of MnAl thin films, and the easy axis changes from perpendicular to parallel direction of the film plane when the annealing temperature varies from 400 °C to 500 °C. MOKE results were also found to be consistent with the magnetic results.
由于锰铝（Mn-Al）薄膜在自旋电子器件中的应用以及作为无稀土磁体，其铁磁性和磁各向异性备受关注。在铁磁性的MnAl薄膜中观察到了与温度相关的单轴各向异性，这归因于随着退火温度的变化四方晶格畸变的改变，振动样品磁强计（VSM）、磁光克尔效应（MOKE）和X射线衍射（XRD）结果证实了这一点；退火时间不影响磁各向异性。采用简单的蒸发技术在砷化镓（GaAs）衬底上沉积了Mn/Al双层薄膜（厚度约为64纳米）。本文报道了对退火温度以及退火时间对结构、微观结构、磁性和磁光性能影响的综合研究。XRD、MOKE和磁滞回线证实，退火样品中富铁磁相。XRD结果表明，退火温度≥400℃时，退火薄膜中铁磁τ相增强。通过原子力显微镜（AFM）显微照片估计表面粗糙度，发现其增加，而对沉积态的Mn/Al双层薄膜进行退火时平均晶粒尺寸减小。发现随着退火温度升高，矫顽力逐渐增加。值得注意的是，通过改变MnAl薄膜的退火温度可以调整磁易轴，当退火温度从400℃变化到500℃时，易轴从垂直于膜平面方向变为平行于膜平面方向。还发现MOKE结果与磁性结果一致。
