亚铁磁GdCo中跨越磁化补偿点的激光诱导皮秒自旋电流的起源
Origin of the laser-induced picosecond spin current across magnetization compensation in ferrimagnetic GdCo
AI总结：
本文通过太赫兹发射光谱研究亚铁磁GdCo中激光诱导的皮秒自旋电流，揭示磁化补偿点处磁畴形成对自旋电流的抑制机制，并阐明Co亚晶格在室温下的主导作用。
摘要：
稀土-过渡金属亚铁磁体所实现的磁性光学操控，为超快、高能效的自旋电子技术带来了希望。本工作通过太赫兹发射光谱，研究了亚铁磁GdCo产生的激光诱导皮秒自旋电流。在存在外加磁场的情况下，当改变温度或合金成分时，在磁化补偿点观察到太赫兹发射和自旋电流受到抑制。研究证明，这是由于GdCo平衡磁构型中磁畴的形成所致。在没有外加磁场时，皮秒自旋电流在补偿点仍然存在。实验发现支持基于热自旋极化电子输运的太赫兹自旋电流产生模型，该模型在室温下由Co亚晶格主导。只有在低温下，才检测到来自Gd的可比贡献，但其动力学过程更慢。最后，光谱分析揭示了与接近磁化补偿时磁畴形成相关的太赫兹发射发生蓝移。
英文摘要：
The optical manipulation of magnetism enabled by rare earth-transition metal ferrimagnets holds the promise of ultrafast, energy efficient spintronic technologies. This work investigates laser-induced picosecond spin currents generated by ferrimagnetic GdCo via terahertz emission spectroscopy. A suppression of the THz emission and spin current is observed at magnetization compensation when varying the temperature or alloy composition in the presence of a magnetic field. It is demonstrated that this is due to the formation of domains in the GdCo equilibrium magnetic configuration. Without an applied magnetic field, the picosecond spin current persists at the compensation point. The experimental findings support the model for THz spin current generation based on transport of hot spin-polarized electrons, which is dominated by the Co sublattice at room temperature. Only at low temperature a comparable contribution from Gd is detected but with slower dynamics. Finally, spectral analysis reveals a blueshift of the THz emission related to the formation of magnetic domains close to magnetization compensation.
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