Anomalous Nernst effect induced terahertz emission in a single ferromagnetic film

TL;DR

This study demonstrates that the anomalous Nernst effect can induce terahertz emission in a single ferromagnetic film, providing new insights into ultrafast magnetism and advancing THz spintronics research.

Contribution

It introduces a quantitative method to distinguish ANE-induced THz emission from other mechanisms, clarifying the origin of ferromagnetic THz emission.

Findings

ANE significantly contributes to THz emission in ferromagnetic films

The method effectively separates different THz emission mechanisms

ANE can overwhelm other competing ultrafast processes

Abstract

By developing a bidirectional-pump terahertz (THz) emission spectroscopy, we reveal an anomalous Nernst effect (ANE) induced THz emission in a single ferromagnetic film. Based on the distinctive symmetry of the THz signals, ANE is unequivocally distinguished from the previously attributed ultrafast demagnetization and anomalous Hall effect mechanisms. A quantitative method is established to separate the different contributions, demonstrating a significant ANE contribution that even overwhelms other competing mechanisms. Our work not only clarifies the origin of the ferromagnetic-based THz emission, but also offers a fertile platform for investigating the ultrafast magnetism and THz spintronics.