Excitation of high-frequency magnon modes in magnetoelastic films by short strain pulses
Excitation of high-frequency magnon modes in magnetoelastic films by short strain pulses
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DOI：
10.1103/physrevmaterials.4.064418
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发表时间：
2020-06-24
影响因子：
3.4
通讯作者：
Pertsev, Nikolay A.
中科院分区：
文献类型：
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作者：
Azovtsev, Andrei, V;Pertsev, Nikolay A.
开发用于产生自旋波（磁振子）的能量有效技术对于实现低耗散基于自旋波的逻辑电路和存储器元件是重要的。实现这一目标的一个有前途的方法是基于短应变脉冲注入到铁磁薄膜的自旋和应变之间的强磁弹性耦合。在这里，我们报告的磁化强度和应变动力学在Fe 81 Ga 19薄膜的皮秒和纳秒的声脉冲在GaAs衬底中产生的换能器受到的光或电脉冲激发的微磁致弹性模拟。通过耦合Landau-Lifshitz-吉尔伯特方程和弹性动力学方程的数值解进行的模拟表明，注入的应变脉冲在铁磁薄膜中引起不均匀的磁化进动。进动持续时间高达1 ns，可以被视为具有自旋驻波形式的磁振子模式的叠加。对于Fe 81 Ga 19薄膜与纳米级的厚度，高达七（六）不同的模式已被揭示自由表面（钉扎）的磁性边界条件下。值得注意的是，磁振子模式的频率超过1太赫兹，可以激发声脉冲与适当的形状和持续时间的薄膜受到一个温和的外部磁场。这一发现表明，短应变脉冲代表了一个有前途的工具，用于产生太赫兹自旋波的实施所需的高速磁振子设备。
The development of energy efficient techniques for the generation of spin waves (magnons) is important for the implementation of low-dissipation spin-wave-based logic circuits and memory elements. A promising approach to achieve this goal is based on the injection of short strain pulses into ferromagnetic films with a strong magnetoelastic coupling between the spins and strains. Here, we report micromagnetoelastic simulations of the magnetization and strain dynamics excited in Fe81Ga19 films by picosecond and nanosecond acoustic pulses created in a GaAs substrate by a transducer subjected to an optical or electrical impulse. The simulations performed via the numerical solution of the coupled Landau-Lifshitz-Gilbert and elastodynamic equations show that the injected strain pulse induces an inhomogeneous magnetization precession in the ferromagnetic film. The precession lasts up to 1 ns and can be treated as a superposition of magnon modes having the form of standing spin waves. For Fe81Ga19 films with a nanoscale thickness, up to seven (six) distinct modes have been revealed under free-surface (pinning) magnetic boundary conditions. Remarkably, magnon modes with frequencies over 1 THz can be excited by acoustic pulses with an appropriate shape and duration in films subjected to a moderate external magnetic field. This finding shows that short strain pulses represent a promising tool for the generation of THz spin waves necessary for the implementation of high-speed magnonic devices.