论文标题
宽带Terahertz的各向异性磁路震动脱离外部和内在贡献的探针
Broadband terahertz probes of anisotropic magnetoresistance disentangle extrinsic and intrinsic contributions
论文作者
论文摘要
各向异性磁阻（AMR）是当代旋转研究中无处不在且多功能的磁性探针。它的起源通常归因于外在效应（即自旋依赖性电子散射），而固有的（即与散射无关）的贡献被忽略了。在这里，我们测量了从DC到28 THz的频率范围内测量标准Ferromagnets Co，Ni，Ni81Fe19和Ni50fe50的多晶薄膜的AMR。较大的带宽涵盖了扩散和弹道内电子传输的机制，因此使我们能够分离外在和内在的AMR组件。基于Boltzmann转运理论的THZ响应的分析表明，Ni，Ni81Fe19和Ni50fe50样品的AMR主要具有外在性质。但是，CO薄膜表现出相当大的内在AMR贡献，该贡献的恒定最高为28 thz，而DC AMR对比度为1％，超过2/3。这些特征归因于Co Crystallites的六边形结构。对于在Terahertz Spintronics和Terahertz光子学中的应用中，它们很有趣。我们的结果表明，宽带Terahertz电磁脉冲为超快时间尺度上标准磁性薄膜的磁电机传输现象提供了新的无接触式见解。
Anisotropic magnetoresistance (AMR) is a ubiquitous and versatile probe of magnetic order in contemporary spintronics research. Its origins are usually ascribed to extrinsic effects (i.e. spin-dependent electron scattering), whereas intrinsic (i.e. scattering-independent) contributions are neglected. Here, we measure AMR of polycrystalline thin films of the standard ferromagnets Co, Ni, Ni81Fe19 and Ni50Fe50 over the frequency range from DC to 28 THz. The large bandwidth covers the regimes of both diffusive and ballistic intraband electron transport and, thus, allows us to separate extrinsic and intrinsic AMR components. Analysis of the THz response based on Boltzmann transport theory reveals that the AMR of the Ni, Ni81Fe19 and Ni50Fe50 samples is of predominantly extrinsic nature. However, the Co thin film exhibits a sizeable intrinsic AMR contribution, which is constant up to 28 THz and amounts to more than 2/3 of the DC AMR contrast of 1%. These features are attributed to the hexagonal structure of the Co crystallites. They are interesting for applications in terahertz spintronics and terahertz photonics. Our results show that broadband terahertz electromagnetic pulses provide new and contact-free insights into magneto-transport phenomena of standard magnetic thin films on ultrafast time scales.
