Khurshid Hafsa, Yoosuf Rahana, Issa Bashar Afif, Attaelmanan Atta G, Hadjipanayis George
Department of Applied Physics and Astronomy, University of Sharjah, Sharjah 27272, United Arab Emirates.
Department of Radiology, Dartmouth Hitchcock Medical Center, Lebanon, NH 03766, USA.
Nanomaterials (Basel). 2021 Nov 12;11(11):3042. doi: 10.3390/nano11113042.
Cobalt nanowires have been synthesized by electrochemical deposition using track-etched anodized aluminum oxide (AAO) templates. Nanowires with varying spacing-to-diameter ratios were prepared, and their magnetic properties were investigated. It is found that the nanowires' easy magnetization direction switches from parallel to perpendicular to the nanowire growth direction when the nanowire's spacing-to-diameter ratio is reduced below 0.7, or when the nanowires' packing density is increased above 5%. Upon further reduction in the spacing-to-diameter ratio, nanowires' magnetic properties exhibit an isotropic behavior. Apart from shape anisotropy, strong dipolar interactions among nanowires facilitate additional uniaxial anisotropy, favoring an easy magnetization direction perpendicular to their growth direction. The magnetic interactions among the nanowires were studied using the standard method of remanence curves. The demagnetization curves and Delta m (Δm) plots showed that the nanowires interact via dipolar interactions that act as an additional uniaxial anisotropy favoring an easy magnetization direction perpendicular to the nanowire growth direction. The broadening of the dipolar component of Δm plots indicate an increase in the switching field distribution with the increase in the nanowires' diameter. Our findings provide an important insight into the magnetic behavior of cobalt nanowires, meaning that it is crucial to design them according to the specific requirements for the application purposes.
通过使用径迹蚀刻阳极氧化铝（AAO）模板进行电化学沉积合成了钴纳米线。制备了具有不同间距与直径比的纳米线，并对其磁性进行了研究。研究发现，当纳米线的间距与直径比降低到0.7以下，或者当纳米线的堆积密度增加到5%以上时，纳米线的易磁化方向从平行于纳米线生长方向转变为垂直于纳米线生长方向。随着间距与直径比的进一步降低，纳米线的磁性表现出各向同性行为。除了形状各向异性外，纳米线之间强烈的偶极相互作用促进了额外的单轴各向异性，有利于形成垂直于其生长方向的易磁化方向。使用剩磁曲线的标准方法研究了纳米线之间的磁相互作用。退磁曲线和Δm（Δm）图表明，纳米线通过偶极相互作用相互作用，这种相互作用充当了额外的单轴各向异性，有利于形成垂直于纳米线生长方向的易磁化方向。Δm图中偶极分量的展宽表明，随着纳米线直径的增加，开关场分布增加。我们的研究结果为钴纳米线的磁行为提供了重要的见解，这意味着根据应用目的的特定要求来设计它们至关重要。
