All-Optical Control of Magnetization in Quantum-Confined Ultrathin Magnetic Metals

TL;DR

This paper investigates how femtosecond laser pulses can control magnetization in ultrathin metallic films with quantum confinement, revealing thickness-dependent dynamics and efficient energy transfer mechanisms.

Contribution

The study introduces a theoretical model showing the high sensitivity of electronic and magnetic properties to film thickness in ultrathin metals, enabling ultrafast magnetization control.

Findings

Magnetization dynamics vary significantly with film thickness.

High efficiency in energy transfer from laser photons to spin waves.

Distinct behaviors compared to bulk metals due to quantum confinement.

Abstract

All-optical control dynamics of magnetization in sub-10 nm metallic thin films are investigated, as these films with quantum confinement undergo unique interactions with femtosecond laser pulses. Our theoretical derivations based on the free electron model show that the density of states at Fermi level (DOS_F) and electron-phonon coupling coefficients (G_ep) in ultrathin metals have very high sensitivity to film thickness within a few Angstroms. As DOS_F and G_ep depend on thickness, we show that completely different magnetization dynamics characteristics emerge compared with bulk metals. Our model suggests highly-efficient energy transfer from fs laser photons to spin waves due to minimal energy absorption by phonon. This sensitivity to thickness and efficient energy transfer offers an opportunity to obtain ultrafast on-chip magnetization dynamics.