Beyazit Y, Beckord J, Zhou P, Meyburg J P, Kühne F, Diesing D, Ligges M, Bovensiepen U
Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
Faculty of Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, 45141 Essen, Germany.
Phys Rev Lett. 2020 Aug 14;125(7):076803. doi: 10.1103/PhysRevLett.125.076803.
Employing femtosecond laser pulses in front and back side pumping of Au/Fe/MgO(001) combined with detection in two-photon photoelectron emission spectroscopy, we analyze local relaxation dynamics of excited electrons in buried Fe, injection into Au across the Fe-Au interface, and electron transport across the Au layer at 0.6 to 2.0 eV above the Fermi energy. By analysis as a function of Au film thickness we obtain the electron lifetimes of bulk Au and Fe and distinguish the relaxation in the heterostructure's constituents. We also show that the excited electrons propagate through Au in a superdiffusive regime and conclude further that electron injection across the epitaxial interface proceeds ballistically by electron wave packet propagation.
利用飞秒激光脉冲对Au/Fe/MgO(001)进行正面和背面泵浦，并结合双光子光电子发射光谱检测，我们分析了埋入Fe中激发电子的局部弛豫动力学、跨Fe-Au界面注入Au的情况以及在费米能级以上0.6至2.0电子伏特时电子在Au层中的传输。通过作为Au膜厚度函数的分析，我们获得了块状Au和Fe的电子寿命，并区分了异质结构各组分中的弛豫情况。我们还表明，激发电子在超扩散状态下通过Au传播，并进一步得出结论，即通过外延界面的电子注入是通过电子波包传播进行的弹道式过程。
