Terahertz Emission from Spintronic Stack Nanodecorated with Drop-Cast Core-Shell Plasmonic Nanoparticles

TL;DR

This paper demonstrates that depositing silica-gold core-shell nanoparticles onto a spintronic THz emitter significantly enhances its terahertz pulse energy, offering a promising route to more efficient THz sources for various technological applications.

Contribution

It introduces a drop-casting method to enhance spintronic THz emitters using plasmonic nanoparticles, achieving higher efficiency through local optical coupling improvements.

Findings

Increased THz pulse energy with nanoparticle decoration

High local conversion enhancement observed

Potential for improved THz emitter efficiency

Abstract

Spintronic emitters promise to revolutionise terahertz (THz) sources by converting ultrafast optical pulses into broadband THz radiation without phase-matching constraints. Because the conversion relies on spin-current injection across a nanometre-thin magnetic layer, its efficiency is ordinarily limited by weak optical coupling. Here, we present a demonstration of a drop-casting based approach to introduce ultrafast plasmonic-mediated coupling: a sparse-layer of silica-gold core-shell nanoparticles is deposited directly onto a W/Fe/Pt spintronic trilayer. This sparse (six percent) decoration increases the wafer-averaged THz pulse energy, pointing to a very high local conversion enhancement for this low-coverage spintronic emitter compared with the bare stack. This demonstration points to a viable pathway toward highly efficient spintronic terahertz emitters with potential applications in spectroscopy, imaging, and ultrafast technologies.