XFEL: Studies on metallic nickel reveal magnetic insights

An international group of scientists have discovered details about the electronic structure of metallic nickel using a technique called time-resolved X-ray absorption spectroscopy (XAS) at European XFEL. Their discovery enables a better understanding of the magnetic properties of nickel, a permanent magnet or ‘ferromagnet’, and can also shed light on how ferromagnetic materials can be manipulated with ultrashort laser pulses. Such insights can help to study other magnetic materials, and to develop more efficient magnetic storage devices.

The scientists used an optical laser to produce charges in the nickel samples. The samples were prepared as thin films mounted in the path of the X-ray beam at the European XFEL’s spectroscopy and coherent scattering (SCS) instrument. As a consequence of the generated charges, the properties of nickel change. The team was able to record these changes using a series of extremely short X-ray pulses, short enough such that ultrafast processes in the material could be observed. The resulting series of snapshots revealed in detail how electrons reorganized themselves in the nickel after the initial ‘kick’ given by the optical laser. In particular, the researchers were interested in understanding the process of ‘ultrafast demagnetization’, where a material’s magnetic properties can be ‘switched-off’ on a timescale of less than a trillionth of a second long.

“Examining permanently magnetic materials, or ferromagnets, under these conditions tells us how the charges in the material interact on a fundamental level, and also how these materials behave as magnets” says Andrea Eschenlohr from the University of Duisburg-Essen, project leader of the study, now published in Materials Research Letters. “Our technique has been applied to nickel as a benchmark, and we are very pleased with the outcomes. Now we hope that we can use time-resolved XAS with such high data quality to gain deeper insights into other magnets, and even more complex materials.”

The study, which was one of the first demonstrations of time-resolved XAS at European XFEL, highlights the unique capabilities of the SCS instrument for such investigations. The team now hope to investigate other materials, in particular to study the behavior of surfaces and interfaces relevant for photovoltaics and the development of photocatalysts.

Read more at link. 

Reference:

“The interplay of local electron correlations and ultrafast spin dynamics in fcc Ni,” Tobias Lojewski, Mohamed F. Elhanoty et al., Mat. Res. Lett. 11, 655-661 (2023), https://doi.org/10.1080/21663831.2023.2210606

Contact:

Dr Andrea Eschenlohr
Tel: +49-203-37-94531
E-mail: andrea.eschenlohr@uni-due.de 

Dr Bernd Ebeling
Tel: +49-40-8998-6921
E-mail: bernd.ebeling@xfel.eu