In ${\mathrm{Ta/(Co,Fe)B/HfO}}_2$ stacks, a gate voltage drives, in a nonvolatile way, the system from an underoxidized state exhibiting in-plane anisotropy (IPA) to an optimum oxidation level resulting in perpendicular anisotropy (PMA) and further into an overoxidized state with IPA. The $\mathrm{IPA}\to \mathrm{PMA}$ regime is found to be significantly faster than the $\mathrm{PMA}\to \mathrm{IPA}$ regime, whereas only the latter shows full reversibility under the same gate voltages. The effective damping parameter also shows a marked dependence with gate voltage in the $\mathrm{IPA}\to \mathrm{PMA}$ regime, going from 0.029 to 0.012, and only a modest increase to 0.014 in the $\mathrm{PMA}\to \mathrm{IPA}$ regime. The existence of two magnetoionic regimes has been linked to a difference in the chemical environment of the anchoring points of oxygen species added to underoxidized or overoxidized layers. Our results show that multiple magnetoionic regimes can exist in a single device and that their characterization is of great importance for the design of high-performance spintronics devices.

中文翻译：

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Ta/Co20Fe60B20/HfO2 中的多重磁离子机制

在 ${\mathrm{Ta/(Co,Fe)B/HfO}}_2$在堆栈中，栅极电压以非易失性方式驱动系统从表现出面内各向异性 (IPA) 的欠氧化状态到导致垂直各向异性 (PMA) 的最佳氧化水平，并进一步进入 IPA 的过氧化状态。这$\mathrm{国际音标}\to \mathrm{聚丙烯酰胺}$ 发现制度明显快于 $\mathrm{聚丙烯酰胺}\to \mathrm{国际音标}$制度，而只有后者在相同的栅极电压下表现出完全可逆性。有效阻尼参数也显示出与栅极电压的显着相关性$\mathrm{国际音标}\to \mathrm{聚丙烯酰胺}$ 制度，从 0.029 到 0.012，并且仅适度增加到 0.014 $\mathrm{聚丙烯酰胺}\to \mathrm{国际音标}$政权。两种磁离子状态的存在与添加到欠氧化或过氧化层的氧物质的锚定点的化学环境的差异有关。我们的结果表明，单个器件中可以存在多个磁离子状态，并且它们的表征对于高性能自旋电子器件的设计非常重要。