Terahertz emission from magnetic thin film and patterned heterostructures
Terahertz emission from magnetic thin film and patterned heterostructures
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DOI：
10.1117/12.2526194
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
S. Lendínez;Yi Li;Wei-Peng Wu;Mojtaba Taghipour Kaffash;Qi Zhang;Wei Zhang;J. Pearson;R. Divan-R.-Di
中科院分区：
文献类型：
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作者：
S. Lendínez;Yi Li;Wei-Peng Wu;Mojtaba Taghipour Kaffash;Qi Zhang;Wei Zhang;J. Pearson;R. Divan-R.-Di
太赫兹(THz)技术是近年来出现的一个具有广泛应用前景的新兴研究领域。在电磁光谱中，太赫兹辐射介于红外辐射和微波辐射之间。到目前为止，大多数太赫兹源与自旋自由度无关；然而，最近在自旋电子学和铁磁性方面的研究表明，电子自旋为产生超快光电流提供了全新的机会。例如，磁性异质结构非常容易图案化，并且潜在地允许通过设计来定制THz发射特性。在这里，我们证明了由飞秒激光脉冲驱动的超快自旋电流脉冲可以由于逆自旋霍尔效应而在微结构磁性异质结构中产生太赫兹瞬变。我们比较了对照CoFeB/铂薄膜与微结构CoFeB/Pt丝以及在扩展的铂薄膜上形成的微结构CoFeB/MgO丝的THz电场和THz谱。我们发现，太赫兹电场的幅度与氧化镁衬底上CoFeB/铂异质结的覆盖率成正比。此外，我们还分析了太赫兹瞬变相对于铁磁线易轴的磁化方向关系。这些结果是通过微结构形成基于自旋电子学的太赫兹发射体来塑造和控制太赫兹特性的第一步。
In recent years terahertz (THz) technology has been an emerging research field with a broad range of applications. THz radiation falls between the infrared and microwave radiation in the electromagnetic spectrum. Most THz sources to date are not related to the spin degree of freedom; however, recent research efforts in spintronics and ferromagnetism demonstrated that the electron spin offers completely new opportunities for the generation of ultrafast photocurrents. For instance, magnetic heterostructures are very easy to pattern and potentially allow to tailor THz emission characteristics by design. Here, we demonstrate that an ultrafast spin-current pulse driven by a femtosecond laser pulse can create THz transients in microstructured magnetic heterostructures due to the inverse spin Hall effect. We compare the THz electric field and the THz spectrum of a control CoFeB/Pt film with microstructured CoFeB/Pt wires as well as microstructured CoFeB/MgO wires patterned on an extended Pt film. We find that the THz electric field amplitude is proportional to the coverage of the CoFeB/Pt heterostructure on top of the MgO substrate. Furthermore, we analyze the magnetization direction dependence of the THz transients with respect to the easy axis of the ferromagnetic wire. The presented results are the first steps towards shaping and controlling the THz properties by microstructuring of spintronics-based THz emitters.