Current‐Enhanced Broadband THz Emission from Spintronic Devices

TLDR

Ultra‑broadband THz emitters spanning 0.1–10 THz are highly desired for spectroscopy, yet spintronic sources, though efficient and broadband, are limited in the 0.1–0.5 THz range. The study demonstrates a current‑enhanced broadband THz emitter that combines spintronic sources with semiconductor materials. A bias current induces photoconduction in the semiconductor, which constructively interferes with inverse spin Hall effect–generated THz signals from the magnetic heterostructure. The hybrid emitter achieves a 2–3‑order‑of‑magnitude boost in the 0.1–0.5 THz range while maintaining comparable high‑frequency performance, advancing ultra‑broadband THz spectroscopy with metallic heterostructure emitters.

Abstract

Abstract An ultra‐broadband terahertz (THz) emitter covering a wide range of frequencies from 0.1 to 10 THz is highly desired for spectroscopy applications. So far, spintronic THz emitters have been proven as one class of efficient THz sources with a broadband spectrum while the performance in the lower THz frequency range (0.1–0.5 THz) limits its applications. In this work, a novel concept of a current‐enhanced broad spectrum from spintronic THz emitters combined with semiconductor materials is demonstrated. A 2–3 order enhancement of the THz signals in a lower THz frequency range (0.1–0.5 THz) is observed, in addition to a comparable performance at higher frequencies from this hybrid emitter. With a bias current, there is a photoconduction contribution from semiconductor materials, which can be constructively interfered with the THz signals generated from the magnetic heterostructures driven by the inverse spin Hall effect (ISHE). These findings push forward the utilization of metallic heterostructure‐based THz emitters on the ultra‐broadband THz emission spectroscopy.