The generation of significant spin imbalance in nonmagnetic semiconductors is crucial for the functioning of many spintronic devices, such as magnetic diodes and transistors, spin-based logic gates, and spin-polarized lasers. An attractive design of spin injectors into semiconductors is based on spin pumping from a precessing ferromagnet, but the classical excitation of magnetization precession by a microwave magnetic field leads to the high-power consumption of the device. Here, we describe theoretically a spin injector with greatly reduced energy losses, in which the magnetic dynamics is excited by an elastic wave generated in a ferromagnet-semiconductor heterostructure by an attached piezoelectric transducer. To demonstrate the efficient functioning of such an injector, we first perform micromagnetoelastic simulations of the coupled elastic and magnetic dynamics in $\mathrm{Ni}$ films and $\mathrm{Ni}/\mathrm{GaAs}$ bilayers traversed by plane longitudinal and shear waves. For thick $\mathrm{Ni}$ films, it is shown that a monochromatic acoustic wave generates a spin wave with the same frequency and wavelength, which propagates together with the driving wave over distances of several micrometers at excitation frequencies $\nu \approx 10$ GHz close to the frequency of ferromagnetic resonance. The simulations of $\mathrm{Ni}/\mathrm{GaAs}$ bilayers with $\mathrm{Ni}$ thicknesses comparable to the wavelength of the injected acoustic wave demonstrate the development of a steady-state magnetization precession at the $\mathrm{Ni}|\mathrm{GaAs}$ interface. The amplitude of such a precession has a maximum at $\mathrm{Ni}$ thickness amounting to three quarters of the wavelength of the elastic wave, which is explained by an analytical model. Using simulation data obtained for the magnetization precession at the $\mathrm{Ni}|\mathrm{GaAs}$ interface, we evaluate the spin current pumped into $\mathrm{GaAs}$ and calculate the spin accumulation in the semiconducting layer by solving the spin diffusion equation. Then the electrical signals resulting from the spin flow and the inverse spin Hall effect are determined via the numerical solution of the Laplace's equation. It is shown that amplitudes of these ac signals near the interface are large enough for experimental measurement, which indicates an efficient acoustically driven spin pumping into $\mathrm{GaAs}$ and a rather high spin accumulation in this semiconductor.

中文翻译：

---

弹性波驱动的半导体高效节能自旋注入器

非磁性半导体中显着的自旋失衡的产生对于许多自旋电子器件的功能至关重要，例如磁性二极管和晶体管，基于自旋的逻辑门和自旋极化激光器。半导体中自旋注入器的一种有吸引力的设计基于来自进动铁磁体的自旋泵浦，但是微波磁场对磁化进动的经典激发导致该设备的高功耗。在这里，我们从理论上描述了一种自旋式喷射器，其能量损失大大降低，其中，磁动力学是由附接的压电换能器在铁磁-半导体异质结构中产生的弹性波激发的。为了证明这种注射器的有效功能，$你$ 电影和 $你/\mathrm{砷化镓}$平面纵波和切变波横穿的双层结构。对于厚$你$ 薄膜，表明单色声波产生具有相同频率和波长的自旋波，该自旋波与驱动波一起在激发频率处传播数微米的距离 $\nu \approx 10$ GHz接近铁磁共振的频率。模拟$你/\mathrm{砷化镓}$ 双层 $你$ 厚度与注入的声波的波长相当，这表明在稳态时磁化旋进的发展。 $你|\mathrm{砷化镓}$界面。进动的幅度在$你$厚度等于弹性波波长的四分之三，这可以通过解析模型来解释。使用获得的模拟数据进行磁化进动$你|\mathrm{砷化镓}$ 界面，我们评估泵入的自旋电流 $\mathrm{砷化镓}$并通过求解自旋扩散方程来计算半导体层中的自旋累积。然后，通过拉普拉斯方程的数值解确定由自旋流和逆自旋霍尔效应产生的电信号。结果表明，界面附近的这些交流信号的幅度足以进行实验测量，这表明有效的声学驱动自旋泵浦到$\mathrm{砷化镓}$ 在这种半导体中有很高的自旋积累。