Terahertz emission from anomalous Hall effect in a single-layer ferromagnet

TL;DR

This paper demonstrates terahertz emission from a single-layer ferromagnet driven by the anomalous Hall effect, showing control via magnetization gradients without needing extra layers or interfaces.

Contribution

It introduces a novel method for THz generation using only a single ferromagnetic layer and the anomalous Hall effect, simplifying device design.

Findings

THz emission is generated by femtosecond laser excitation of the ferromagnet.

Magnetization gradients can modulate the amplitude and polarity of the THz emission.

The method does not require additional non-magnetic layers or Rashba interfaces.

Abstract

We report on terahertz emission from a single layer ferromagnet which involves the generation of backflow nonthermal charge current from the ferromagnet/dielectric interface by femtosecond laser excitation and subsequent conversion of the charge current to a transverse transient charge current via the anomalous Hall effect, thereby generating the THz radiation. The THz emission can be either enhanced or suppressed, or even the polarity can be reversed, by introducing a magnetization gradient in the thickness direction of the ferromagnet. Unlike spintronic THz emitters reported previously, it does not require additional non-magnetic layer or Rashba interface.