Effective Magnetic Switching of THz Signal in Planar Structured Spintronic Emitters

TL;DR

This paper demonstrates a method for efficiently switching the THz emission in spintronic bilayer structures by controlling magnetization orientation, achieving significant amplitude modulation and polarization control.

Contribution

It introduces a structured spintronic emitter with micro- or nanostripes that enables magnetic control of THz emission amplitude and polarization.

Findings

Achieved up to 27-fold amplitude change in THz emission.

Controlled THz polarization aligned with stripe direction.

Demonstrated magnetic re-magnetization as a switch for THz emission.

Abstract

We demonstrate an efficient swithcable spintronic THz emission from a Co(2nm)/Pt(2nm) bilayer split into a grating of micro- or nanostripes in applied external magnetic field of the order of 10mT. The THz signal is effectively emitted if the samples are magnetized perpendicular to the stripes direction and decreases upon a 90-degree rotation of a sample. The maximal 27-fold ratio of amplitude change is achieved for the sample with a $2 \mu m$ width of stripes. For the samples with easy magnetization axis directed perpendicular to stripes the THz signal is linearly polarized in the direction of the stripes and abruptly switches during the sample re-magnetization process. If the easy axis is along the stripes the THz source is almost switched off in a zero magnetic field.