Magnetoresistive random-access memory (MRAM) relies on magnetic tunnel junctions (MTJs) comprising heterostructures of CoFeB/MgO/CoFeB. Nonetheless, the dielectric breakdown of MgO limits the lifespan of MRAM devices. In the current study, we terminated MgO with a Mg surface facing the CoFeB free layer to reduce the mismatch in band alignment across the barrier. The Mg-modified interface was shown to enhance the breakdown voltage while reducing the switching current and asymmetric switching behavior, with a moderate sacrifice of perpendicular magnetic anisotropy, tunneling magnetoresistance, and resistance–area product. This performance trade-off was observed in all MTJs, regardless of cell size (180, 130, and 80 nm; each size has been tested with at least 20 cells). Visualization of the proposed junction viain situ X-ray absorption spectroscopy proved effective in elucidating the reconstruction of the interface within the context of energy barrier height, asymmetric switching behavior, and the voltage-driven movement of oxygen ions. A spin-dependent band diagram was constructed to correlate the tunneling/switching properties of the MTJ with such a trade-off scenario. The atomistic simulation of the magnetic properties revealed that Mg termination lowered the switching energy barrier with an effective domain wall motion within the CoFeB free layer.

中文翻译：

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原位 X 射线探索的自旋转移扭矩记忆的插入权衡效应

磁阻随机存取存储器 (MRAM) 依赖于包含 CoFeB/MgO/CoFeB 异质结构的磁性隧道结 (MTJ)。尽管如此，MgO 的介电击穿限制了 MRAM 器件的寿命。在当前的研究中，我们用面向 CoFeB 自由层的 Mg 表面终止 MgO，以减少跨越势垒的能带对准的不匹配。Mg 改性界面被证明可以提高击穿电压，同时降低开关电流和不对称开关行为，并适度牺牲垂直磁各向异性、隧道磁阻和电阻面积积。无论单元尺寸如何（180、130 和 80 nm；每种尺寸均已使用至少 20 个单元进行了测试），在所有 MTJ 中都观察到了这种性能折衷。所提出的结可视化通过原位X 射线吸收光谱证明在能垒高度、不对称切换行为和电压驱动的氧离子运动的背景下重建界面是有效的。构建了一个与自旋相关的带图，以将 MTJ 的隧道/开关特性与这种权衡方案相关联。磁性能的原子模拟表明，Mg 终止降低了开关能垒，并在 CoFeB 自由层内产生了有效的畴壁运动。