Abstract

We describe the development of a broadband magneto-optical spectrometer with femtosecond temporal resolution. The absorption spectrometer is based on a white-light supercontinuum (∼320 to 750 nm) using shot-to-shot temporal and spectral referencing at 1 kHz. Static and transient absorption spectra using circularly polarized light are collected in a magnetic field. The difference spectra with respect to the external field direction give the static and transient magneto-optical Faraday rotation (magnetic optical rotary dispersion) and ellipticity (magnetic circular dichroism) spectra. An achromatic quarter-wave plate is used, and the impact of the deviation from ideal retardance on the spectra is discussed. Results from solution-based and thin-film samples are used to demonstrate the performance and wide applicability of the instrument. The sensitivities for the static and time-resolved data were found to be 5 and 0.4 mdeg, respectively. The method presents a simple way to measure magneto-optical spectra using a transient absorption spectrometer and an electromagnet.

Highlights

  • Such research has been made possible through femtosecond magneto-optics, where the time-dependent change in polarisation state of a probe pulse in the presence of a magnetised material is recorded

  • We describe a broadband time-resolved MCD (TRMCD) spectrometer in transmission (Faraday) geometry

  • The transient absorption spectrometer used in this work is described in Ref. and is based on the one described in Ref

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Summary

A Femtosecond Magnetic Circular Dichroism Spectrometer

Jake Sutcliffe[1] and J. We describe the development of a broadband magneto-optical spectrometer with femtosecond temporal resolution. The absorption spectrometer is based on a white-light supercontinuum 320 − 750 nm) using shot-to-shot temporal and spectral referencing at 1 kHz. Static and transient absorption spectra using circularly polarised light are collected in a magnetic field. The difference spectra with respect to the external field direction give the static and transient magneto-optical Faraday rotation (magnetic optical rotary dispersion) and ellipticity (magnetic circular dichroism) spectra. Results from solution-based and thin-film samples are used to demonstrate the performance and wide applicability of the instrument. The sensitivities for the static and time-resolved data were found to be 5 and 0.4 mdeg, respectively. The method presents a simple way to measure magneto-optical spectra using a transient absorption spectrometer and an electromagnet

INTRODUCTION
METHODOLOGY
Faraday Rotation
Faraday Ellipticity
Ferromagnetic Thin Films
TIME-RESOLVED MEASUREMENTS
CONCLUSION
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