Directional Magnetization Reversal Enables Ultrahigh Energy Density in Gradient Nanostructures
Directional Magnetization Reversal Enables Ultrahigh Energy Density in Gradient Nanostructures
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DOI：
10.1002/adma.202102800
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发表时间：
2021-07-26
影响因子：
29.4
通讯作者：
Zhang, Xiangyi
中科院分区：
文献类型：
--
作者：
Lou, Li;Li, Yuqing;Zhang, Xiangyi
高性能铁磁材料是能量转换和电子器件必不可少的材料。然而，铁磁性材料的随机和非均匀磁化反转限制了它们的性能。在这里，通过微磁模拟和实验，通过工程Nd2Fe14B/ α - fe梯度纳米结构，发现了从大颗粒向小颗粒的定向磁化反转。这种定向磁化反转使得高磁化强度和大矫顽力的罕见结合成为可能，从而导致各向同性永磁材料的能量密度达到创纪录的26 MG Oe，比无梯度的材料高出约50%。不寻常的磁化反转源于梯度材料中晶粒尺寸的有序排列，其中大晶粒的反转场比小晶粒的反转场低。这些发现为开发高性能磁性材料开辟了新的机会。
High-performance ferromagnetic materials are essential for energy conversion and electronic devices. However, the random and nonuniform magnetization reversal in ferromagnetics limits their performance that can be achieved. Here, through both micromagnetism simulations and experiments, a directional magnetization reversal that initiates first from large grains toward smaller ones is discovered by engineering Nd2Fe14B/alpha-Fe gradient nanostructures. Such directional magnetization reversal enables a rare combination of high magnetization and large coercivity, thus leading to a record-high energy density (26 MG Oe) for isotropic permanent magnetic materials, which is approximate to 50% higher than that of its gradient-free counterpart. The unusual magnetization reversal originates from an ordered arrangement of grain sizes in the gradient material, where the large grains have a lower reversal field than that of the smaller ones. These findings open up new opportunities for developing high-performance magnetic materials.