Scientific Reports ( IF 3.8 ) Pub Date : 2023-08-18 , DOI: 10.1038/s41598-023-40515-9 Abir Shadman 1 , Jian-Gang Zhu 1
Utilizing micromagnetic modeling, we have explained the unprobed characteristics of 360° full cycle in-plane magnetization rotation and the resulting propagation of a magnetization wave along a ferromagnet nanowire. The magnetization wave, which is generated by setting off spin oscillation at one end of a ferromagnetic strip, propagates till the end of the wire. A perpendicular spin torque oscillator (STO) could generate magnetization rotation at one end of the ferromagnetic strip that is also part of the STO. Our results demonstrate that the oscillation frequency of the spins along the wire maintains excellent fidelity while the spatial wavelength of the magnetic wave increases. The driving mechanism behind the propagation of the wave is found to be exchange-springs, which enables the propagation of the wave without the need for a 'carrier' force, such as spin-transfer torque (STT) or spin Hall effect (SHE). Furthermore, we demonstrate that the gradient of the exchange energy drives the magnetic wave forward, while the in and out of plane anisotropy fields govern the shape of spin oscillation trajectories along the wire. Additionally, we show that stopping the oscillation at the STO end causes the wave to cease propagation after relaxation, and altering the STO rotational chirality leads to merging and annihilating domain walls of opposite winding numbers.
中文翻译:
关于纳米线中面内磁化旋转和磁化波传播的微磁见解
利用微磁模型,我们解释了 360° 全周期面内磁化旋转的未探测特性以及由此产生的磁化波沿着铁磁体纳米线的传播。通过在铁磁条一端引发自旋振荡而产生的磁化波传播到导线的末端。垂直自旋扭矩振荡器 (STO) 可以在铁磁条的一端产生磁化旋转,铁磁条也是 STO 的一部分。我们的结果表明,当磁波的空间波长增加时,沿导线的自旋振荡频率保持优异的保真度。人们发现波传播背后的驱动机制是交换弹簧,它无需“载体”力即可实现波的传播,例如自旋转移矩(STT)或自旋霍尔效应(SHE) 。此外,我们证明交换能量的梯度驱动磁波前进,而平面内和平面外各向异性场控制沿导线的自旋振荡轨迹的形状。此外,我们还发现,在 STO 端停止振荡会导致波在弛豫后停止传播,而改变 STO 旋转手性会导致相反缠绕数的磁畴壁的合并和湮灭。