磁子自旋转移力矩驱动的畴壁纳米振荡器
摘要
<p indent="0mm">Spin waves (SWs) and domain walls (DWs) have been two prominent research fields in the history of magnetism, which remain active in unfolding spintronics. In the past decades, rich novel dynamic effects have been revealed in the exploration of SWs and DWs in magnetic nanostructures, promising important applications in new-generation magnetic devices. Due to the absence of Joule heat, SWs are considered as candidates for information carriers with ultra-low power consumption. DW dynamics at the nanoscale, besides its fundamental interests, also bears significance in terms of technology applications. A spin nano-oscillator is a new type of spintronic device, which has advantages such as small size, wide frequency modulation range, and easy integration compared to traditional semiconductor oscillators. Former spin nano-oscillators are usually driven by spin polarized electric current via the so-called spin-transfer torque effect. In a typical spin nano-oscillator, the magnetization of the free layer of a spin valve (SV) or a magnetic tunneling junction (MTJ) is driven by electric currents to sustain a continuous precession, with the damping of the system compensated by the current. Highly tunable microwave signals can be generated during the oscillation. In a current-driven DW nano-oscillator proposed recently, the free layer of a SV or MTJ is replaced by a transverse DW pinned in a ferromagnetic nanowire, which oscillates periodically subject to a spin-transfer torque exerted by a current passing through the DW. It has been pointed out that SWs also carry spin currents and thus spin angular momentum, which can as well be transferred to local magnetic structures, such as DWs, during its transportation. This effect is referred to as the magnonic spin-transfer torque. Previous studies have been focused on ferromagnetic thin-films, in which a translational motion of the DW is found to be induced by the electric current. In this work, we study the SW-driven