Researchers from the Jerzy Haber Institute of Catalysis and Surface Chemistry of the Polish Academy of Sciences in Kraków have carried out advanced experiments using angle-resolved photoemission spectroscopy (ARPES). They discovered a new surface state of iron Fe(001), whose symmetry changes depending on the magnetization direction of the layer. The results of their study have been published in the prestigious New Journal of Physics.

The electronic band structure of iron has been investigated for decades, but earlier studies were limited by experimental constraints. Today, with access to high-resolution ARPES facilities, such as the Phelix beamline at the Solaris synchrotron in Kraków, scientists can explore the electronic states of materials with unprecedented precision.

For the first time, the existence of a surface state on Fe(001) was unambiguously demonstrated in the epitaxial Fe/Au(001) system. Moreover, the Kraków team was the first to map this state across the full range of energy and momentum. Previous experiments, for example on Fe(001)/W(001), had been restricted to only a few high-symmetry directions or normal emission. By examining the surface state throughout the Brillouin zone, the researchers identified specific regions where spin–orbit coupling modifies the surface electronic states depending on the magnetization direction.

This phenomenon, confirmed by density functional theory calculations performed by theorists from Forschungszentrum Jülich (Germany) and the University of Amsterdam, was interpreted as a manifestation of the Rashba effect – a key mechanism in modern spintronics. The study lies at the intersection of solid-state physics, surface science, and spintronics, opening new perspectives for the design of functional multilayer structures containing Fe(001).

This work was funded by the National Science Centre, Poland (NCN), Sonata Bis grant number 2022/46/E/ST3/00184.

Figure 1. Surface state of Fe(001)/Au(001) within entire Brillouin zone and Rashba effect at the zone boudary.

Author: Ewa Młyńczak

Link to the publication: Ewa Młyńczak, Ardra Surendran, SMIBIN SHAJU, Kinga Freindl, Józef Korecki, Ewa Madej, Dorota Wilgocka-Ślęzak, Magdalena Szczepanik, Tomasz Sobol, Irene Aguilera, Gustav Bihlmayer, Stefan Blügel and Nika Spiridis Spin–orbit effects in the surface state of Fe(001) revealed by full surface Brillouin zone mapping New J. Phys. 27 (2025) 093506, DOI 10.1088/1367-2630/ae05be