Spin wave excitation by spin-polarized electric current in all-metallic and tunnel magnetic junctions

电流感应磁开关描述了由于自旋极化传导电子与薄膜磁矩的相互作用而引起的磁膜磁化方向的变化，目前被认为是下一代磁记忆的潜在开关机制。然而，这种相互作用也会导致非均匀激励的放大。本课题是研究自旋极化电流引起的自旋波激发和放大过程。实验将在具有反铁磁层间耦合的金属磁性层状系统中实现：自旋波将在一个特殊设计的毫瓦腔中由微波频率的交流电流激发，从而使电场和磁场在空间上分离。这样就排除了在点接触实验中不可避免的毫瓦磁场自旋波激发的寄生效应。自旋极化电流的空间调制将产生具有明确波矢量的自旋波。利用短脉冲电流和时间分辨布里渊光散射光谱研究激发过程的动力学。通过改变电流脉冲与自旋波检测时间矩之间的时间延迟，研究了自旋波与电流脉冲相互作用时强度的增长及其随之产生的衰减。

Current induced magnetic switching describing the change in the direction of magnetization of a magnetic film due to interaction of spin-polarized conduction electrons with the film's magnetic moments is considered now as a potential switching mechanism for next generations of magnetic memory. This interaction, however, should also lead to the amplification of non-uniform excitations. The subject of the project is to investigate the process of spin wave excitation and amplification caused by the spin polarized current. The experiment will be realized in metallic magnetic layered systems with anti ferromagnetic interlayer coupling: spin waves will be excited by an ac current of microwave frequency in a specially designed MW cavity allowing for a spatial separation of electric and magnetic fields. Thus, the parasitic effect of spin wave excitation by the MW magnetic field, unavoidable in point contact experiments, will be excluded. A spatial modulation of the spin polarized current will generate spin waves of well defined wave vector. Using short pulses of electric current and time resolved Brillouin light scattering spectroscopy the dynamics of the excitation process will be studied. Changing the time delay between the current pulse and the time moment of the spin wave detection, the growth of the spin wave intensity due to interaction with the current pulse and their consequent decay will be investigated.