论文标题
PY/石墨烯/PT的自旋注入特性，由Gigahertz和Terahertz磁化动力学由飞秒激光脉冲驱动
Spin injection characteristics of Py/graphene/Pt by gigahertz and terahertz magnetization dynamics driven by femtosecond laser pulse
论文作者
论文摘要
到目前为止，已经对石墨烯的自旋传输特性进行了广泛的研究。但是，沿C轴的自旋运输据报道有限数量。我们通过石墨烯沿C轴研究了旋转传输特性，该轴是由Gigahertz（GHz）和Terahertz（THZ）（THZ）磁化动力学的，由飞秒激光脉冲驱动的动力学。相对简单的样品结构不需要样品上的电极。石墨烯层是通过化学蒸气沉积制备的，并在PT膜上转移。石墨烯层的质量以拉曼显微镜为特征。时间解析的磁光kerr效应用于表征Gigahertz磁化动力学。对于PT/PY和PT/GR/PY，可以清楚地观察到磁化进动。 PT/PY的Gilbert阻尼常数为0.015，表明从PY到PT的旋转泵浦效果。发现PT/GR/PY的Gilbert阻尼常数为0.011，表明自旋注射被石墨烯层阻止。我们还对PT/PY和PT/GR/PY进行了THZ发射的测量。虽然对于PT/PY清楚地观察到了THZ发射，但对于PT/GR/PY，观察到THZ发射的强烈降低。通过这两个不同的实验和高度各向异性石墨的电阻率，我们得出结论，垂直自旋转运被石墨烯层强烈抑制。
Spin transport characteristics of graphene has been extensively studied so far. The spin transport along c-axis is however reported by rather limited number of papers. We have studied spin transport characteristics through graphene along c-axis with permalloy(Py)/graphene(Gr)/Pt by gigahertz (GHz) and terahertz (THz) magnetization dynamics driven by femtosecond laser pulses. The relatively simple sample structure does not require electrodes on the sample. The graphene layer was prepared by chemical vapor deposition and transferred on Pt film. The quality of graphene layer was characterized by Raman microscopy. Time resolved magneto-optical Kerr effect is used to characterize gigahertz magnetization dynamics. Magnetization precession is clearly observed both for Pt/Py and Pt/Gr/Py. The Gilbert damping constant of Pt/Py was 0.015, indicates spin pumping effect from Py to Pt. The Gilbert damping constant of Pt/Gr/Py is found to be 0.011, indicates spin injection is blocked by graphene layer. We have also performed the measurement of THz emission for Pt/Py and Pt/Gr/Py. While the THz emission is clearly observed for Pt/Py, a strong reduction of THz emission is observed for Pt/Gr/Py. With these two different experiments, and highly anisotropic resistivity of graphite, we conclude that the vertical spin transport is strongly suppressed by the graphene layer.
