Zhang Junli, Zhu Shimeng, Xia Weixing, Ming Jun, Li Fashen, Fu Jiecai
Key Laboratory of Magnetism and Magnetic Materials of the Ministry of Education, School of Physical Science and Technology , Lanzhou University , Lanzhou 730000 , P. R. China.
Key Laboratory of Magnetic Materials and Devices , Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences , Ningbo 315201 , P. R. China.
ACS Appl Mater Interfaces. 2019 Aug 7;11(31):28442-28448. doi: 10.1021/acsami.9b07502. Epub 2019 Jul 24.
Magnetic nanostructures with flux-closure state or single-domain state have widespread application in diverse memory devices. However, an insight into the modulation of these variable states within one specific magnetic material is rarely reported but still needed. Herein, these micromagnetic configurations within prototypical cobalt ferrite (CoFeO) nanostructures in different size and dimension were studied by modulating the assembly of CoFeO building blocks. We find that the CoFeO nanowire (NW) has a multidomain structure when the diameter is about 90 nm, in which the domain walls (DWs) locate preferentially at the grain boundary and can convert to single-domain state when the diameter is reduced. Alternatively, a flux-closure domain state is obtained when the CoFeO nanostructure changes from NW to nanosheet (NS), where the DWs location depends on the overall shape of NS. In addition, we further confirm that the magnetic anisotropy and magnetostatic energy are two main factors affecting the micromagnetic configuration in CoFeO nanostructures by crystallographic analysis and micromagnetic simulations. Our experimental and simulation results demonstrate that the modulation of morphology and dimension are efficient to tailor the micromagnetic configuration in magnetic nanostructures.
具有磁通闭合状态或单畴状态的磁性纳米结构在各种存储器件中有着广泛的应用。然而，关于在一种特定磁性材料中对这些可变状态进行调制的深入研究很少被报道，但仍然是需要的。在此，通过调节钴铁氧体（CoFeO）结构单元的组装，研究了不同尺寸和维度的典型钴铁氧体（CoFeO）纳米结构中的这些微磁构型。我们发现，当直径约为90 nm时，CoFeO纳米线（NW）具有多畴结构，其中畴壁（DWs）优先位于晶界处，当直径减小时可转变为单畴状态。或者，当CoFeO纳米结构从NW转变为纳米片（NS）时，可获得磁通闭合畴状态，其中DWs的位置取决于NS的整体形状。此外，我们通过晶体学分析和微磁模拟进一步证实，磁各向异性和静磁能是影响CoFeO纳米结构中微磁构型的两个主要因素。我们的实验和模拟结果表明，形态和尺寸的调制对于定制磁性纳米结构中的微磁构型是有效的。
