Highly-efficient spintronic terahertz emitter enabled by metal-dielectric photonic crystal

Abstract

Spintronic terahertz (THz) emitter provides the advantages such as apparently broader spectrum, significantly lower cost, and more flexibility in compared with the commercial THz emitters, and thus attracts great interests recently. In past few years, efforts have been made in optimizing the material composition and structure geometry, and the conversion efficiency has been improved close to that of ZnTe crystal. One of the drawbacks of the current designs is the rather limited laser absorption - more than 50% energy is wasted and the conversion efficiency is thus limited. Here, we theoretically propose and experimentally demonstrate a novel device that fully utilizes the laser intensity and significantly improves the conversion efficiency. The device, which consists of a metal-dielectric photonic crystal structure, utilizes the interference between the multiple scattering waves to simultaneously suppress the reflection and transmission of the laser, and to reshape the laser field distributions. The experimentally detected laser absorption and THz generations show one-to-one correspondence with the theoretical calculations. We achieve the strongest THz pulse emission that presents a 1.7 times improvement compared to the currently designed spintronic emitter. This work opens a new pathway to improve the performance of spintronic THz emitter from the perspective of optics.

arXiv comment22 pages,4 figures

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• Modification of spintronic terahertz emitter performance through defect engineering
• Interface reflectivity of a superdiffusive spin current in ultrafast demagnetization and THz emission
• Spintronic THz emitters based on transition metals and semi-metals/Pt multilayers
• Transfer Matrix description of heterostructured spintronics Terahertz emission
• Maximizing the electromagnetic efficiency of spintronic terahertz emitters
• Modelling of Spintronic Terahertz Emitters as a function of spin generation and diffusion geometry
• Laser-driven few-cycle Terahertz sources with high average power
• Ghost spintronic THz-emitter-array microscope
• Enhancement of Spintronic Terahertz Emission via Annealing in Ferromagnetic Heterostructures
• High-efficiency Pt${}_{75}$Au${}_{25}$-based spintronic terahertz emitters