Controlling polarization of spintronic THz emitter by remanent magnetization texture

TL;DR

This paper demonstrates a switchable spintronic THz emitter whose polarization can be precisely controlled by the magnetization texture shaped by microstructure, enabling tunable and on-chip THz device applications.

Contribution

It introduces a method to control THz emission polarization via remanent magnetization textures in micropatterned magnetic heterostructures, revealing physical mechanisms of ultrafast spin current generation.

Findings

Polarization of THz emission is tunable by magnetization texture.

Switching of THz emission can be achieved by magnetic saturation.

Physical insights into nonuniform magnetization effects on spin currents.

Abstract

Terahertz (THz) sciences and technologies have contributed to a rapid development of a wide range of applications and expanded the frontiers in fundamental science. Spintronic terahertz emitters offer conceptual advantages since the spin orientation in the magnetic layer can be easily controlled either by the externally applied magnetic field or by the internal magnetic field distribution determined by the specific shape of the magnetic elements. Here, we report a switchable terahertz source based on micropatterned magnetic heterostructures driven by femtosecond laser pulses. We show that the precise tunability of the polarization state is facilitated by the underlying magnetization texture of the magnetic layer that is dictated by the shape of the microstructure. These results also reveal the underlying physical mechanisms of a nonuniform magnetization state on the generation of ultrafast spin currents in the magnetic heterostructures. Our findings indicate that the emission of the linearly polarized THz waves can be switched on and off by saturating the sample using a biasing magnetic field, opening fascinating perspectives for integrated on-chip THz devices with wide-ranging potential applications.