Spin valve as THz emitter providing amplitude modulation

Abstract

We present a novel spin-valve THz emitter composed of FeCo/TbCo2/FeCo tri-layers separated by a copper spacer, designed to provide amplitude modulation of THz radiation. The distinct coercivities of the magnetic layers enable magnetic field control of the THz emission, with the final amplitude formed by the interference of THz waves from the individual tri-layers. Experimental studies using time-domain spectroscopy reveal that the spin-valve structure, optimized for in-plane magnetic anisotropy, effectively modulates the THz signal and maintains constant polarization. Although the current optical-to-THz conversion efficiency is insufficient for commercial use, the findings offer crucial insights for enhancing efficiency through structural optimization, highlighting the potential for advanced THz emitters and modulators.