Decker Régis, Born Artur, Büchner Robby, Ruotsalainen Kari, Stråhlman Christian, Neppl Stefan, Haverkamp Robert, Pietzsch Annette, Föhlisch Alexander
Institute for Methods and Instrumentation for Synchrotron Radiation Research FG-ISRR, Helmholtz-Zentrum Berlin für Materialien und Energie Albert-Einstein-Strasse 15, 12489, Berlin, Germany.
Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476, Potsdam, Germany.
Sci Rep. 2019 Jun 20;9(1):8977. doi: 10.1038/s41598-019-45242-8.
While extensive work has been dedicated to the measurement of the demagnetization time following an ultra-short laser pulse, experimental studies of its underlying microscopic mechanisms are still scarce. In transition metal ferromagnets, one of the main mechanism is the spin-flip of conduction electrons driven by electron-phonon scattering. Here, we present an original experimental method to monitor the electron-phonon mediated spin-flip scattering rate in nickel through the stringent atomic symmetry selection rules of x-ray emission spectroscopy. Increasing the phonon population leads to a waning of the 3d → 2p decay peak intensity, which reflects an increase of the angular momentum transfer scattering rate attributed to spin-flip. We find a spin relaxation time scale in the order of 50 fs in the 3d-band of nickel at room temperature, while consistantly, no such peak evolution is observed for the diamagnetic counterexample copper, using the same method.
尽管已有大量工作致力于测量超短激光脉冲后的退磁时间，但其潜在微观机制的实验研究仍然匮乏。在过渡金属铁磁体中，主要机制之一是由电子 - 声子散射驱动的传导电子自旋翻转。在此，我们提出一种原始实验方法，通过X射线发射光谱严格的原子对称性选择规则来监测镍中电子 - 声子介导的自旋翻转散射率。增加声子数量会导致3d→2p衰变峰强度减弱，这反映了归因于自旋翻转的角动量转移散射率增加。我们发现在室温下镍的3d能带中自旋弛豫时间尺度约为50飞秒，同时，使用相同方法对抗磁性的铜进行测量时，未观察到此类峰的演变。
