What is it about?

This research looks at the X-ray reflectivity during a hysteresis cycle from a thin magnetic permalloy (iron and nickel) film. By tuning to the iron L3 absoprtion edge the reflectivity becomes sensitive to the iron magnetisation. This was measured for different polarisations i.e. with the incident polarisation set to linear horizontal (sigma), linear vertical (pi), circular left and circular right.

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Why is it important?

The results indicate that the profile of the reflectivity during a hysteresis cycle do not always resemble magnetisation due to a non-linear dependence on the magnetic moment of the ions. This depends strongly on both polarisation and energy. This is important since hysteresis curves measured with reflectivity (or any scattering technique) could look much more complicated than the underlying magnetisation. This study will help researchers to understand the profile of hysteresis curves measured with reflectivity and other X-ray scattering techniques which is important for measuring the underlying reversal processes with depth resolution and element specificity.


It is hoped that the results from both the data and the calculations will help researchers when studying magnetism with resonant magnetic scattering. This could help with the detailed unravelling of the hysteresis behaviour in thin films, and other systems, ultimately leading to an improved understanding.

Paul Steadman
Diamond Light Source

Read the Original

This page is a summary of: Measuring magnetic hysteresis curves with polarized soft X-ray resonant reflectivity, Journal of Synchrotron Radiation, April 2024, International Union of Crystallography,
DOI: 10.1107/s160057752400119x.
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