论文标题
超薄石榴石中铁磁共振的光学引起的频率上转换
Optically-induced frequency up-conversion of the ferromagnetic resonance in an ultrathin garnet
论文作者
论文摘要
我们在带有垂直磁各向异性的纳米厚的晶体双型Yttrium铁石榴石膜上进行超快的泵送测量。调整泵激光脉冲的光子能量上方和下方的带脉冲脉冲的光子能量，我们通过一种和两光子的吸收触发了超快的光学和自旋动力学。与常见情况相反，系统的光学加热可引起高达20％的铁磁共振频率的增加。我们用光引起的磁各向异性修饰（即有效场）来解释这一意外结果，从而确定了观察到这种影响的必要条件。我们的结果揭示了在纳米厚磁体中光学上增加磁性特征频率的可能性。
We perform ultrafast pump-probe measurements on a nanometer-thick crystalline Bi-doped yttrium iron garnet film with perpendicular magnetic anisotropy. Tuning the photon energy of the pump laser pulses above and below the material's bandgap, we trigger ultrafast optical and spin dynamics via both one- and two-photon absorption. Contrary to the common scenario, the optically-induced heating of the system induces an increase up to 20% of the ferromagnetic resonance frequency. We explain this unexpected result in terms of a photo-induced modification of the magnetic anisotropy, i.e. of the effective field, identifying the necessary conditions to observe this effect. Our results disclose the possibility to optically increase the magnetic eigenfrequency in nanometer-thick magnets.
