论文标题
在由超快自旋相互作用触发的抗铁磁绝缘子中发射相干THZ
Emission of coherent THz magnons in an antiferromagnetic insulator triggered by ultrafast spin-phonon interactions
论文作者
论文摘要
由于其超快自旋动力学，已经提出了抗铁磁材料作为新型窄带THZ Spintronic设备。但是，操纵其旋转动态仍然是一个关键的挑战，这是通过旋转轨道扭矩或直接的光激发来实现的关键挑战。在这里，我们在Nio/Pt的低阻尼薄膜中以1 Thz的形式展示了宽带THz（不一致）磁子（不一致）的磁子和窄带（相干）磁子的组合产生。我们在实验和建模中证明了NiO中磁化动力学的两个激发过程，一种非谐振瞬时光学自旋扭矩以及由超快PT激发引起的应变波诱导的THZ扭矩。这两种现象都通过相邻重金属层中的反旋转大厅效应发出THZ信号。我们分别揭示了两个激发过程的特征时间尺度，分别<50 fs和> 300 fs，从而开放了基于抗磁磁材料的快速光旋转设备开发的新途径。
Antiferromagnetic materials have been proposed as new types of narrowband THz spintronic devices owing to their ultrafast spin dynamics. Manipulating coherently their spin dynamics, however, remains a key challenge that is envisioned to be accomplished by spin-orbit torques or direct optical excitations. Here, we demonstrate the combined generation of broadband THz (incoherent) magnons and narrowband (coherent) magnons at 1 THz in low damping thin films of NiO/Pt. We evidence, experimentally and through modelling, two excitation processes of magnetization dynamics in NiO, an off-resonant instantaneous optical spin torque and a strain-wave-induced THz torque induced by ultrafast Pt excitation. Both phenomena lead to the emission of a THz signal through the inverse spin Hall effect in the adjacent heavy metal layer. We unravel the characteristic timescales of the two excitation processes found to be < 50 fs and > 300 fs, respectively, and thus open new routes towards the development of fast opto-spintronic devices based on antiferromagnetic materials.
