Hild K, Maul J, Schönhense G, Elmers H J, Amft M, Oppeneer P M
Institut für Physik, Staudinger Weg 7, Universität Mainz, D-55128 Mainz, Germany.
Phys Rev Lett. 2009 Feb 6;102(5):057207. doi: 10.1103/PhysRevLett.102.057207.
We report the observation of magnetic circular dichroism (MCD) in two-photon photoemission (2PPE). The Heusler alloys Ni2MnGa and Co2FeSi were investigated by excitation with femtosecond laser light, showing MCD asymmetries of A=(3.5+/-0.5)x10;{-3} for Ni2MnGa and of A=(2.1+/-1.0)x10;{-3} for Co2FeSi, respectively. A theoretical explanation is provided based on local spin-density calculations for the magnetic dichroic response; the computed 2PPE MCD agrees well with the experiment. The observed 2PPE magnetic contrast represents an interesting alternative for future time-resolved photoemission studies on surface magnetism practicable in the laboratory.
我们报告了在双光子光电发射（2PPE）中对磁圆二色性（MCD）的观测。通过飞秒激光激发对赫斯勒合金Ni2MnGa和Co2FeSi进行了研究，结果表明Ni2MnGa的MCD不对称性A = (3.5 ± 0.5)×10⁻³，Co2FeSi的A = (2.1 ± 1.0)×10⁻³。基于对磁二向色性响应的局域自旋密度计算提供了理论解释；计算得到的2PPE MCD与实验结果吻合良好。所观测到的2PPE磁对比度为未来在实验室中可行的表面磁性时间分辨光电子能谱研究提供了一种有趣的选择。
