Magneto-ionics is a fast developing research field which opens the perspective of energy efficient magnetic devices, where the magnetization direction is controlled by an electric field which drives the migration of ionic species. In this work, the interfacial perpendicular magnetic anisotropy (PMA) of Pt/Co/oxide stacks covered by ZrO₂, acting as a ionic conductor, is tuned by a gate voltage at room temperature. A large variation of the PMA is obtained by modifying the oxidation of the cobalt layer through the migration of oxygen ions: the easy magnetization axis can be switched reversibly from in-plane, with under-oxidized Co, to in-plane, with over-oxidized Co, passing through an out-of-plane magnetization state. The switching time between the different magnetic states is limited by the ion drift velocity. This depends exponentially on the gate voltage, and is varied by over five orders of magnitude, from several minutes to a few ms. The variation of the PMA versus time during the application of the gate voltage can be modeled with a parabolic variation of the PMA and an exponential decrease of the Co oxidation rate. The possibility to explain the observed effect with a simple theoretical model opens the possibility to engineer materials with optimized properties.

中文翻译：

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Pt/Co/Oxide 多层磁各向异性的电场驱动操作中的离子迁移动力学

磁离子是一个快速发展的研究领域，它开启了高效磁器件的前景，其中磁化方向由驱动离子物种迁移的电场控制。在这项工作中，ZrO ₂覆盖的 Pt/Co/氧化物叠层的界面垂直磁各向异性 (PMA)充当离子导体，在室温下由栅极电压调节。通过氧离子的迁移改变钴层的氧化，获得了 PMA 的很大变化：易磁化轴可以可逆地从面内、氧化不足的 Co 到面内、过度氧化的 Co氧化的 Co，通过面外磁化状态。不同磁态之间的切换时间受离子漂移速度的限制。这与栅极电压呈指数关系，变化幅度超过五个数量级，从几分钟到几毫秒不等。在施加栅极电压期间 PMA 随时间的变化可以用 PMA 的抛物线变化和 Co 氧化速率的指数下降来建模。