Wide-field magneto-optical microscope to access quantitative magnetization dynamics with femtosecond temporal and sub-micrometer spatial resolution

TL;DR

This paper presents a wide-field magneto-optical microscope capable of capturing ultrafast magnetization dynamics with high spatial resolution, enabling detailed analysis of laser-induced magnetic switching in materials.

Contribution

The paper introduces a novel wide-field magneto-optical microscope with calibrated non-linear response, allowing direct quantitative mapping of magnetization with femtosecond and sub-micrometer resolution.

Findings

Successful calibration of the magneto-optical response.

Direct mapping of magnetization from intensity data.

Observation of non-linear magnetization dynamics across fluence regions.

Abstract

We introduce a wide-field magneto-optical microscope to probe magnetization dynamics with femtosecond temporal and sub-micrometer spatial resolution. We carefully calibrate the non-linear dependency between the magnetization of the sample and the detected light intensity by determining the absolute values of the magneto-optical polarization rotation. With that, an analytical transfer function is defined to directly map the recorded intensity to the corresponding magnetization, which results in significantly reduced acquisition times and relaxed computational requirements. The performance of the instrument is characterized by probing the magnetic all-optical switching dynamics of GdFe in a pump-probe experiment. The high spatial resolution of the microscope allows for accurately subdividing the laser-excited area into different fluence-regions in order to capture the strongly non-linear magnetization dynamics as a function of the optical pump intensity in a single measurement.