AI 中文总结
本文研究CoHo亚铁磁合金中飞秒激光诱导的Co 3d与Ho 4f自旋动力学，测得Ho退磁时间长于Co，支持畴壁介导的全光翻转开关的条件
AI 中文摘要
过渡金属（TM）/稀土（RE）合金近来作为模型体系重新受到关注，用于阐明飞秒激光脉冲引发的全光无 helicity 依赖翻转（AO-HIS）的起源。近期，在CoDy、CoHo合金及Co/Gd超薄膜双层中，已报道一种基于畴壁运动与合并的独特单脉冲磁化翻转机制。研究称，当Co亚晶格完全退磁，且稀土（Gd、Dy或Ho）亚晶格的特征退磁时间τRE长于Co亚晶格，同时转移至Co的角动量减少时，可实现这种特定的翻转开关。对CoDy合金的元素分辨与时间分辨X射线光谱研究显示，室温下Co的特征退磁时间τCo=0.2 ps，Dy的特征退磁时间τDy=0.6 ps。同理，Ho预计表现出更慢的响应，但其超快4f自旋动力学尚未经实验探究。本文报道对亚铁磁Co₈₀Ho₂₀合金中飞秒激光诱导的Co 3d与Ho 4f自旋超快动力学的元素分辨与时间分辨研究，以验证该预测。观测到室温下Co的特征退磁时间τCo=0.22±0.01 ps，Ho的特征退磁时间τHo=0.87±0.15 ps。结果表明，在Co₈₀Ho₂₀中Ho的退磁速率远慢于Co，支持畴壁介导的全光翻转开关的 proposed 条件
英文摘要
The transition metal (TM) / rare-earth (RE) alloys have received renewed interest lately as model systems to decipher the origin of all-optical helicity-independent switching (AO-HIS) by femtosecond laser pulses. Recently, a distinct single-pulse magnetization reversal mechanism, based on domain-wall motion and coalescence, has been reported in CoDy and CoHo alloys, as well as in Co/Gd ultrathin bilayers. It has been claimed that this specific toggle switching is achieved when the Co sublattice is fully demagnetized and the characteristic demagnetization times τRE of the RE (Gd, Dy or Ho) sublattices is longer than that of the Co and the angular momentum transferred to Co is reduced. Element- and time-resolved X-ray spectroscopy studies of CoDy alloys have reported characteristic demagnetization times of τCo = 0.2 ps and τDy = 0.6 ps at room temperature. Similarly, Ho is expected to exhibit a slower response, but its ultrafast 4f spin dynamics remain experimentally unexplored. Here, we report on element- and time-resolved investigations of femtosecond laser induced ultrafast dynamics of the Co 3d and Ho 4f spins in ferrimagnetic Co_{80}Ho_{20} alloys to verify this prediction. We observed characteristic demagnetization times τCo = 0.22 +/- 0.01 ps and τHo = 0.87 +/- 0.15 ps at room temperature. These results show that Ho demagnetizes substantially more slowly than Co in Co_{80}Ho_{20}, supporting the proposed condition for domain-wall-mediated all-optical toggle switching
Comments11 pages, 3 figures, regular article
