Fan Lisha, Gao Xiang, Farmer Thomas O, Lee Dongkyu, Guo Er-Jia, Mu Sai, Wang Kai, Fitzsimmons Michael R, Chisholm Matthew F, Ward Thomas Z, Eres Gyula, Lee Ho Nyung
Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang, 310023, China.
Nanomaterials (Basel). 2020 Mar 5;10(3):472. doi: 10.3390/nano10030472.
Micrometer-tall vertically aligned single-crystalline CoFeO nanobrush architectures with extraordinarily large aspect ratio have been achieved by the precise control of a kinetic and thermodynamic non-equilibrium pulsed laser epitaxy process. Direct observations by scanning transmission electron microscopy reveal that the nanobrush crystal is mostly defect-free by nature, and epitaxially connected to the substrate through a continuous 2D interface layer. In contrast, periodic dislocations and lattice defects such as anti-phase boundaries and twin boundaries are frequently observed in the 2D interface layer, suggesting that interface misfit strain relaxation under a non-equilibrium growth condition plays a critical role in the self-assembly of such artificial architectures. Magnetic property measurements have found that the nanobrushes exhibit a saturation magnetization value of 6.16 B/f.u., which is much higher than the bulk value. The discovery not only enables insights into an effective route for fabricating unconventional high-quality nanostructures, but also demonstrates a novel magnetic architecture with potential applications in nanomagnetic devices.
通过对动力学和热力学非平衡脉冲激光外延过程的精确控制，已实现了具有超大纵横比的微米级垂直排列的单晶CoFeO纳米刷结构。扫描透射电子显微镜的直接观察表明，纳米刷晶体本质上大多无缺陷，并通过连续的二维界面层与衬底外延连接。相比之下，在二维界面层中经常观察到周期性位错和晶格缺陷，如反相边界和孪晶边界，这表明非平衡生长条件下的界面失配应变弛豫在此类人工结构的自组装中起关键作用。磁性测量发现，纳米刷的饱和磁化强度值为6.16 μB/f.u.，远高于块体值。这一发现不仅有助于深入了解制造非常规高质量纳米结构的有效途径，还展示了一种在纳米磁器件中具有潜在应用的新型磁结构。
