The various memory applications such as embedded nonvolatile memory, embedded static random-access memory, and standalone dynamic random-access memory have different requirements for the performance of the perpendicular magnetic tunnel junction (pMTJ). However, in conventional pMTJ structures, the write current and stability of the free layer are directly coupled, leading to undesirable tradeoffs in performance specifications such as endurance and data retention. With the introduction of the precessional spin-current (PSC) structure, we demonstrate a significant gain in the spin transfer torque (STT) efficiency. The PSC structure shows similar critical current values as the conventional pMTJ structure. But we observe a significant increase in thermal stability, which is largely responsible for the enhancement in the STT efficiency. Smaller device dimensions show higher efficiency increase. We confirm the higher data retention time in a thermally activated switching experiment at 180 °C. The PSC structure exhibits more than two decades lower thermal decay rates within 100 h of wait over the conventional pMTJ. These results demonstrate that it is possible to achieve the necessary retention times at high-temperature operation without increasing the power consumption or higher current in normal operation. Furthermore, we demonstrate that even for short write pulsewidth, the switching currents of the PSC structure remain similar to the pMTJ structure while still having better retention.

中文翻译：

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利用进动自旋电流结构的垂直磁化磁性随机存取存储器单元：对现代存储器应用的好处


嵌入式非易失性存储器、嵌入式静态随机存取存储器和独立动态随机存取存储器等各种存储器应用对垂直磁隧道结（pMTJ）的性能有不同的要求。然而，在传统的 pMTJ 结构中，写入电流和自由层的稳定性直接耦合，导致在耐久性和数据保留等性能规格方面出现不良的折衷。通过引入进动自旋流（PSC）结构，我们证明了自旋转移矩（STT）效率的显着增益。 PSC 结构显示出与传统 pMTJ 结构相似的临界电流值。但我们观察到热稳定性显着提高，这在很大程度上是 STT 效率提高的原因。器件尺寸越小，效率提升越高。我们在 180 °C 的热激活开关实验中确认了更高的数据保留时间。 PSC 结构在 100 小时的等待时间内表现出比传统 pMTJ 低二十多年的热衰减率。这些结果表明，可以在高温操作下实现必要的保留时间，而不会增加正常操作中的功耗或更高的电流。此外，我们证明，即使对于短写入脉冲宽度，PSC 结构的开关电流仍与 pMTJ 结构相似，同时仍具有更好的保持能力。