Current-Induced Skyrmion Generation through Morphological Thermal Transitions in Chiral Ferromagnetic Heterostructures
Current-Induced Skyrmion Generation through Morphological Thermal Transitions in Chiral Ferromagnetic Heterostructures
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DOI：
10.1002/adma.201805461
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发表时间：
2018-12-06
影响因子：
29.4
通讯作者：
Beach, Geoffrey S. D.
中科院分区：
文献类型：
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作者：
Lemesh, Ivan;Litzius, Kai;Beach, Geoffrey S. D.
磁性斯格明子由于其固有的稳定性和小尺寸，有望在未来的内存和计算设备中取得突破。最近在室温下观察到了它们的产生和电流驱动的运动，但它们形成的关键机制尚不清楚。这里表明，在重金属/铁磁体异质结构中，脉冲电流可以驱动迷宫状、条纹状和斯格明子态之间的形态转变。使用高分辨率 X 射线显微镜，对自旋织构随温度和磁场的演变进行成像，并证明通过瞬态焦耳加热，可以将拓扑电荷注入系统中，驱动其穿过条纹-斯格明子边界。这些观察结果是通过原子自旋动力学和微磁模拟来解释的，这些模拟揭示了与阈值磁场之上的全局斯格明子基态的交叉，人们发现阈值磁场随着温度的升高而减小。演示了如何通过调整相位稳定性，通过短电流脉冲可靠地生成斯格明子并将其稳定在零场，从而提供了在工程手性铁磁体中创建和操纵自旋纹理的新方法。
Magnetic skyrmions promise breakthroughs in future memory and computing devices due to their inherent stability and small size. Their creation and current driven motion have been recently observed at room temperature, but the key mechanisms of their formation are not yet well-understood. Here it is shown that in heavy metal/ferromagnet heterostructures, pulsed currents can drive morphological transitions between labyrinth-like, stripe-like, and skyrmionic states. Using high-resolution X-ray microscopy, the spin texture evolution with temperature and magnetic field is imaged and it is demonstrated that with transient Joule heating, topological charges can be injected into the system, driving it across the stripe-skyrmion boundary. The observations are explained through atomistic spin dynamic and micromagnetic simulations that reveal a crossover to a global skyrmionic ground state above a threshold magnetic field, which is found to decrease with increasing temperature. It is demonstrated how by tuning the phase stability, one can reliably generate skyrmions by short current pulses and stabilize them at zero field, providing new means to create and manipulate spin textures in engineered chiral ferromagnets.