Anomalous Nernst Effect Induced Terahertz Emission in a Single Ferromagnetic Film
Journal
Nano Letters
Journal Volume
23
Journal Issue
17
Start Page
8171
End Page
8179
ISSN
1530-6984
1530-6992
Date Issued
2023-08-28
Author(s)
Zheng Feng
Wei Tan
Zuanming Jin
Yi-Jia Chen
Zhangfeng Zhong
Liang Zhang
Song Sun
Jin Tang
Yexing Jiang
Po-Hsun Wu
Jun Cheng
Bingfeng Miao
Haifeng Ding
Dacheng Wang
Yiming Zhu
Liang Guo
Sunmi Shin
Guo-Hong Ma
Dazhi Hou
Abstract
Despite its important role in understanding ultrafast spin dynamics and revealing novel spin/orbit effects, the mechanism of the terahertz (THz) emission from a single ferromagnetic nanofilm upon a femtosecond laser pump still remains elusive. Recent experiments have shown exotic symmetry, which is not expected from the routinely adopted mechanism of ultrafast demagnetization. Here, by developing a bidirectional pump-THz emission spectroscopy and associated symmetry analysis method, we set a benchmark for the experimental distinction of the THz emission induced by various mechanisms. Our results unambiguously unveil a new mechanism─anomalous Nernst effect (ANE) induced THz emission due to the ultrafast temperature gradient created by a femtosecond laser. Quantitative analysis shows that the THz emission exhibits interesting thickness dependence where different mechanisms dominate at different thickness ranges. Our work not only clarifies the origin of the ferromagnetic-based THz emission but also offers a fertile platform for investigating the ultrafast optomagnetism and THz spintronics.
Subjects
Anomalous Nernst effect
Ferromagnet
Nanofilm
Spintronic
Terahertz emission
Ultrafast magnetism
SDGs
Publisher
American Chemical Society (ACS)
Type
journal article