Tunable Short-Wavelength Spin-Wave Emission and Confinement in Anisotropy-Modulated Multiferroic Heterostructures
Tunable Short-Wavelength Spin-Wave Emission and Confinement in Anisotropy-Modulated Multiferroic Heterostructures
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DOI：
10.1103/physrevapplied.8.014020
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发表时间：
2017-07-21
影响因子：
4.6
通讯作者：
van Dijken, Sebastiaan
中科院分区：
文献类型：
--
作者：
Hamalainen, Sampo J.;Brandl, Florian;van Dijken, Sebastiaan
我们报道了在具有周期性调制磁各向异性的连续薄膜中短波自旋波的产生和限制。对于应变耦合的Co40Fe40B20/BaTiO3异质结，这一概念依赖于磁条磁畴边界的磁各向异性的突然旋转。在外加偏置磁场的作用下，磁各向异性的这种调制产生有效磁场的横向变化，当受到微波磁场照射时，导致局部自旋波激发。在有效场较小的磁区中，自旋波被相邻磁区中的自旋能隙完全限制。相反，具有较大有效场的磁区中的驻留自旋波辐射到邻近磁区。利用微磁模拟，我们证明了发射的自旋波的波长可以通过旋转偏置场从几个微米到大约100 nm来调节。重要的是，波阵面的方向保持不变。我们还证明了有效磁场的动态涨落在单各向异性边界上产生了交换主导的自旋波。本文提出的多铁性异质结可以利用微波天线的全局激励场，在连续铁磁薄膜的精确位置从纳米宽的线源发射可调谐的自旋波。
We report on the generation and confinement of short-wavelength spin waves in a continuous film with periodically modulated magnetic anisotropy. The concept, which is demonstrated for strain-coupled Co40Fe40B20/BaTiO3 heterostructures, relies on abrupt rotation of magnetic anisotropy at the boundaries of magnetic stripe domains. In combination with an external bias field, this modulation of magnetic anisotropy produces a lateral variation of the effective magnetic field, leading to local spin-wave excitation when irradiated by a microwave magnetic field. In domains with small effective field, spin waves are perfectly confined by the spin gap in neighboring domains. In contrast, standing spin waves in domains with large effective field radiate into neighboring domains. Using micromagnetic simulation, we show that the wavelength of emitted spin waves is tunable from a few micrometers down to about 100 nm by rotation of the bias field. Importantly, the orientation of the wave front remains fixed. We also demonstrate that dynamic fluctuations of the effective magnetic field produce exchange-dominated spin waves at single-anisotropy boundaries. The multiferroic heterostructures presented here enable the use of global excitation fields from a microwave antenna to emit tunable spin waves from a nanometer-wide line source at well-defined locations of a continuous ferromagnetic film.