Magnetic alloy spintronic THz emitters

频率范围为0.3至30 THz的电磁辐射对于基础科学研究中的光谱学和成像以及质量控制、安全技术和电信等应用非常有用。超快自旋电子发射体是一种新型的太赫兹辐射源。通常，它们是铁磁/非磁性系统，如Fe/Pt，依赖于逆自旋霍尔效应。用飞秒激光脉冲泵浦这种结构，将自旋电流从磁性层发射到非磁性层。在那里，逆自旋霍尔效应随后将自旋电流转换为超快电荷电流，其充当宽带THz辐射源。最近，缺乏单一界面层的磁性合金系统的第一个实验结果表明，需要全面了解太赫兹产生机制。该联合项目的目标是系统地研究磁性合金自旋电子THz发射器，并了解THz产生的基本过程。我们将制备各种成分的不同磁性合金，并测量非磁性重元素对低温下瞬态THz发射的影响。此外，我们将研究由于磁性/非磁性双层自旋电子太赫兹发射器的界面混合的太赫兹发射特性的演变，通过逐步进行离子辐照，以最终创建一个均匀的磁性合金。最后，我们将研究化学有序合金中元素的化学结构和分布对太赫兹发射的影响。

Electromagnetic radiation in the frequency range from 0.3 to 30 THz is highly useful for spectroscopy and imaging in fundamental scientific research, as well as for applications such as quality control, security technologies and telecommunications. Ultrafast spintronic emitters represent a new type of THz sources. Commonly, they are ferromagnetic/non-magnetic systems such as Fe/Pt, relying on the inverse spin Hall effect. Pumping this structure with a femtosecond laser pulse launches a spin current from the magnetic into the non-magnetic layer. There, the inverse spin Hall effect subsequently converts the spin current into an ultrafast charge current, which acts as a source of broadband THz radiation. Recently, first experimental results on magnetic alloy systems lacking a single interface layer have demonstrated the need for a comprehensive understanding of the THz generation mechanism(s). The goal of this joint project is to systematically investigate magnetic alloy spintronic THz emitters and to gain an understanding of the underlying THz generation process(es). We will prepare different magnetic alloys of various compositions and measure the impact of non-magnetic heavy elements on the transient THz emission down to cryogenic temperatures. Furthermore, we will study the evolution of the THz emission characteristics due to interface intermixing of magnetic/non-magnetic bilayer spintronic THz emitters, by stepwise performing ion-irradiation in order to eventually create a homogenous magnetic alloy. Finally, we will study the impact of the chemical structure and distribution of the elements in a chemically ordered alloy on the THz emission.