Picosecond x-ray magnetic circular dichroism spectroscopy at the Fe L-edges with a laser-driven plasma source

TL;DR

This paper presents a novel laser-driven plasma source enabling time-resolved x-ray magnetic circular dichroism spectroscopy at the Fe L edges in a laboratory setting, with potential for broad ultrafast magnetic studies.

Contribution

It introduces a new laboratory-based method for soft-x-ray XMCD spectroscopy using a laser-driven plasma source, expanding access beyond synchrotrons and free-electron lasers.

Findings

First XMCD spectroscopy at Fe L edges in a lab setting

Circularly polarized soft x-ray photons generated with a plasma source

Temporal resolution of less than 10 picoseconds

Abstract

Time-resolved x-ray magnetic circular dichroism (XMCD) enables a unique spectroscopic view on complex spin and charge dynamics in multi-elemental magnetic materials. So far, its application in the soft-x-ray range has been limited to synchrotron-radiation sources and free-electron lasers. By combining a laser-driven plasma source with a magnetic thin-film polarizer, we generate circularly polarized photons in the soft x-ray regime, enabling the first XMCD spectroscopy at the Fe L edges in a laser laboratory. Our approach can be readily adapted to other transition metal L and rare earth M absorption edges and with a temporal resolution of < 10 ps, a wide range of ultrafast magnetization studies can be realized.