Hybrid Magnetodynamical Modes in a Single Magnetostrictive Nanomagnet on a Piezoelectric Substrate Arising from Magnetoelastic Modulation of Precessional Dynamics

Magnetoelastic (or "straintronic") switching has emerged as an extremely energy-efficient mechanism for switching the magnetization of magnetostrictive nanomagnets in magnetic memory and logic, and non-Boolean circuits. Here, we investigate the ultrafast magnetodynamics associated with straintronic switching in a single quasielliptical magnetostrictive Co nanomagnet deposited on a piezoelectric Pb(Mg1/3Nb2/3)-O-3-PbTiO3 substrate using time-resolved magneto-optical Kerr effect (TR-MOKE) measurements. The pulsed laser pump beam in the TR-MOKE plays a dual role: it causes precession of the nanomagnet's magnetization about an applied bias magnetic field and it also generates surface acoustic waves in the piezoelectric substrate that produce periodic strains in the magnetostrictive nanomagnet and modulate the precessional dynamics. This modulation gives rise to intriguing hybrid magnetodynamical modes in the nanomagnet, with spin-wave The characteristic frequencies of these modes are 5-15 GHz, indicating that strain can affect magnetization in a magnetostrictive nanomagnet in time scales much smaller than 1 ns (similar to 100 ps). This can enable similar to 10 GHz range magnetoelastic nano-oscillators that are actuated by strain instead of a spin-polarized current, as well as ultrafast magnetoelectric generation of spin waves for magnonic logic circuits, holograms, etc.

磁弹性（或“应变电子”）开关已成为一种在磁存储器、逻辑器件以及非布尔电路中切换磁致伸缩纳米磁体磁化的极节能机制。在此，我们利用时间分辨磁光克尔效应（TR - MOKE）测量方法，研究了沉积在压电Pb(Mg₁/₃Nb₂/₃) - O - 3 - PbTiO₃衬底上的单个准椭圆形磁致伸缩钴纳米磁体中与应变电子开关相关的超快磁动力学。TR - MOKE中的脉冲激光泵浦光束具有双重作用：它使纳米磁体的磁化围绕施加的偏置磁场进动，并且还在压电衬底中产生表面声波，这些表面声波在磁致伸缩纳米磁体中产生周期性应变并调制进动动力学。这种调制在纳米磁体中产生了有趣的混合磁动力学模式，伴有自旋波。这些模式的特征频率为5 - 15 GHz，这表明应变能够在远小于1 ns（约100 ps）的时间尺度上影响磁致伸缩纳米磁体中的磁化。这能够实现类似于由应变而非自旋极化电流驱动的10 GHz范围的磁弹性纳米振荡器，以及用于磁子逻辑电路、全息图等的自旋波的超快磁电产生。