Recently, ferromagnetic-heterostructure spintronic terahertz (THz) emitters have been recognized as one of the most promising candidates for next-generation THz sources, owing to their peculiarities of high efficiency, high stability, low cost, ultrabroad bandwidth, controllable polarization, and high scalability. Despite the substantial efforts, they rely on external magnetic fields to initiate the spin-to-charge conversion, which hitherto greatly limits their proliferation as practical devices. Here, a unique antiferromagnetic–ferromagnetic (IrMn₃|Co₂₀Fe₆₀B₂₀) heterostructure is innovated, and it is demonstrated that it can efficiently generate THz radiation without any external magnetic field. It is assigned to the exchange bias or interfacial exchange coupling effect and enhanced anisotropy. By precisely balancing the exchange bias effect and enhanced THz radiation efficiency, an optimized 5.6 nm-thick IrMn₃|Co₂₀Fe₆₀B₂₀|W trilayer heterostructure is successfully realized, yielding an intensity surpassing that of Pt|Co₂₀Fe₆₀B₂₀|W. Moreover, the intensity of THz emission is further boosted by togethering the trilayer sample and bilayer sample. Besides, the THz polarization may be flexibly controlled by rotating the sample azimuthal angle, manifesting sophisticated active THz field manipulation capability. The field-free coherent THz emission that is demonstrated here shines light on the development of spintronic THz optoelectronic devices.

中文翻译：

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基于反铁磁-铁磁异质结构的无场太赫兹发射器

近年来，铁磁异质结构自旋电子太赫兹（THz）发射器因其高效率、高稳定性、低成本、超宽带宽、可控极化和高效率等特点而被公认为下一代太赫兹源最有希望的候选者之一。可扩展性。尽管付出了巨大的努力，但它们仍依赖外部磁场来启动自旋电荷转换，这极大地限制了它们作为实用器件的扩散。在这里，一种独特的反铁磁-铁磁（IrMn ₃ |Co ₂₀ Fe ₆₀ B ₂₀)异质结构进行了创新，证明它可以在没有任何外部磁场的情况下有效地产生太赫兹辐射。它归因于交换偏差或界面交换耦合效应和增强的各向异性。通过精确平衡交换偏置效应和增强的太赫兹辐射效率，成功实现了优化的 5.6 nm 厚的 IrMn ₃ |Co ₂₀ Fe ₆₀ B ₂₀ |W 三层异质结构，其强度超过了 Pt|Co ₂₀ Fe ₆₀ B ₂₀|W。此外，通过将三层样品和双层样品结合在一起，进一步提高了太赫兹发射的强度。此外，通过旋转样品方位角可以灵活控制太赫兹极化，表现出复杂的主动太赫兹场操纵能力。这里展示的无场相干太赫兹发射照亮了自旋电子太赫兹光电器件的发展。