THz-driven demagnetization with Perpendicular Magnetic Anisotropy: Towards ultrafast ballistic switching

TL;DR

This study demonstrates that intense THz radiation can induce significant ultrafast demagnetization and potentially enable full magnetization reversal in perpendicular magnetic anisotropy materials, paving the way for tabletop ultrafast magnetic switching.

Contribution

We show that THz-driven spin dynamics in perpendicular anisotropy films can achieve substantial demagnetization and propose a meta-material design to enhance THz magnetic fields for ultrafast switching.

Findings

Demagnetization amplitude of about 1% at 300 kV/cm THz field

Enhanced magnetic fields exceeding 1 Tesla with meta-materials

Potential for ultrafast ballistic magnetization reversal

Abstract

We study THz-driven spin dynamics in thin CoPt films with perpendicular magnetic anisotropy. Femtosecond magneto-optical Kerr effect measurements show that demagnetization amplitude of about $1\%$ can be achieved with a peak THz electric field of $300$~kV/cm, and a corresponding peak magnetic field of $0.1$~T. The effect is more than an order of magnitude larger than observed in samples with easy-plane anisotropy irradiated with the same field strength. We also utilize finite-element simulations to design a meta-material structure that can enhance the THz magnetic field by more than an order of magnitude, over an area of several tens of square micrometers. Magnetic fields exceeding $1$~Tesla, generated in such meta-materials with the available laser-based THz sources, are expected to produce full magnetization reversal via ultrafast ballistic precession driven by the THz radiation. Our results demonstrate the possibility of table-top ultrafast magnetization reversal induced by THz radiation.