Engineering of interfacial structures has become important more than ever before to find new scientific observations and to create novel applications. Here, we show that the interface reconstructed by atomic layer-thick Mg insertion substantially improved the magneto-electrical properties of perpendicular magnetic tunnel junctions essential for modern spintronic applications. The 0.2–0.4 nm-thick Mg inserted between the MgO tunnel barrier and CoFeB ferromagnet restructured the interface in such ways as to protect the CoFeB from overoxidation, to strengthen the texture, to make the interfacial roughness smooth, and to relax the mechanical stress. Observed were great increases in the perpendicular magnetic moment and perpendicular magnetic anisotropy of the CoFeB by 2.1 and 1.8 times, respectively, which can be ascribed to the optimum interfacial condition because of the least possible chemical damage. The strong enhancement of (010) in-plane and (001) out-of-plane texture and of interfacial roughness led to a significant increase in the tunnel magnetoresistance by 4.4 times from 13.2 to 57.6% by the insertion. Most importantly, such optimum chemical and physical structures at the interface could modulate the perpendicular magnetic properties by an electric field. The electric field-controlled magnetic anisotropy coefficients became symmetrically bipolar to the electric field and were increased over 100 fJ/V·m, which is 6 times larger than one found before the Mg insertion. As a result, we could successfully demonstrate the voltage-induced magnetization switching of the perpendicular magnetic tunnel junctions with the help of an external magnetic field. Our findings will ignite further study on the new way of electrical control over magnetic switching and provide an essential ingredient to realize electric field-driven energy-effective magneto-electronic devices.

中文翻译：

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通过界面重构在基于MgO / CoFeB的磁性隧道结中的电压辅助磁性开关

寻找新的科学观察结果和创造新颖的应用，界面结构的工程设计比以往任何时候都变得更加重要。在这里，我们表明，通过原子层厚的Mg插入重建的界面大大改善了现代自旋电子学应用必不可少的垂直磁隧道结的磁电性能。在MgO隧道势垒和CoFeB铁磁体之间插入的0.2-0.4 nm厚的Mg以保护CoFeB免受过氧化，增强织构，使界面粗糙度光滑并缓解机械应力的方式重组了界面。观察到CoFeB的垂直磁矩和垂直磁各向异性分别大大增加了2.1倍和1.8倍，由于最小的化学损伤，可以将其归因于最佳界面条件。（010）面内和（001）面外纹理以及界面粗糙度的强烈增强导致通过插入使隧道磁阻显着增加了4.4倍，从13.2增至57.6％。最重要的是，界面处的这种最佳化学和物理结构可以通过电场来调制垂直磁特性。电场控制的磁各向异性系数相对于电场对称地变成双极性的，并且在超过100 fJ / V·m的范围内增加，这是插入Mg之前的6倍。因此，我们可以在外部磁场的帮助下成功演示垂直磁隧道结的电压感应磁化切换。我们的发现将激发对电磁开关电气控制新方法的进一步研究，并为实现电场驱动的节能磁电器件提供必要的要素。