# Broadband spintronic detection of the absolute field strength of terahertz electromagnetic pulses

**Authors:** A. L. Chekhov, Y. Behovits, U. Martens, B. R. Serrano, M. Wolf, T. S. Seifert, M. Muenzenberg, T. Kampfrath  
**arXiv:** [2306.09734](https://arxiv.org/abs/2306.09734)  
**Date:** 2023-06-16  
**Summary page:** https://www.summarizepaper.com/fr/paper/2306.09734v1/

## Abstract

We demonstrate detection of broadband intense terahertz electromagnetic pulses by Zeeman-torque sampling (ZTS). Our approach is based on magneto-optic probing of the Zeeman torque the terahertz magnetic field exerts on the magnetization of a ferromagnet. Using an 8 nm thick iron film as sensor, we detect pulses from a silicon-based spintronic terahertz emitter with bandwidth 0.1-11 THz and peak field >0.1 MV/cm. Static calibration provides access to absolute transient THz field strengths. We show relevant added values of ZTS compared to electro-optic sampling (EOS): an absolute and echo-free transfer function with simple frequency dependence, linearity even at high terahertz field amplitudes, the straightforward calibration of EOS response functions and the modulation of the polarization-sensitive direction by an external AC magnetic field. Consequently, ZTS has interesting applications even beyond the accurate characterization of broadband high-field terahertz pulses for nonlinear terahertz spectroscopy.