Nanoscale mapping of ultrafast magnetization dynamics with femtosecond Lorentz microscopy

TL;DR

This paper introduces femtosecond Lorentz microscopy, a novel imaging technique that combines high spatial and temporal resolution to observe ultrafast magnetization dynamics at the nanoscale, enabling detailed studies of magnetic phenomena.

Contribution

The paper presents a new femtosecond Lorentz microscopy method that achieves sub-100 nm spatial and 700 fs temporal resolution for ultrafast magnetic imaging.

Findings

Successfully mapped light-induced demagnetization of magnetic vortices

Quantified magnetization evolution after optical excitation

Optimized imaging conditions for nanoscale magnetic dynamics

Abstract

Novel time-resolved imaging techniques for the investigation of ultrafast nanoscale magnetization dynamics are indispensable for further developments in light-controlled magnetism. Here, we introduce femtosecond Lorentz microscopy, achieving a spatial resolution below 100 nm and a temporal resolution of 700 fs, which gives access to the transiently excited state of the spin system on femtosecond timescales and its subsequent relaxation dynamics. We demonstrate the capabilities of this technique by spatio-temporally mapping the light-induced demagnetization of a single magnetic vortex structure and quantitatively extracting the evolution of the magnetization field after optical excitation. Tunable electron imaging conditions allow for an optimization of spatial resolution or field sensitivity, enabling future investigations of ultrafast internal dynamics of magnetic topological defects on 10-nanometer length scales.