Humboldt Fellow Alexander Gray comes to HZB
Alexander Gray (here in his lab at Temple University, Philadelphia, USA) will strengthen his collaboration with the team of Florian Kronast at BESSY II. © Privat
Alexander Gray from Temple University in Philadelphia, USA, is working with HZB physicist Florian Kronast to investigate novel 2D quantum materials at BESSY II. With the fellowship from the Alexander von Humboldt Foundation, he can now deepen this cooperation. At BESSY II, he wants to further develop depth-resolved X-ray microscopic and spectroscopic methods in order to investigate 2D quantum materials and devices for new information technologies even more thoroughly.
Topological insulators and Weyl semimetals are among the most exciting classes of materials for quantum devices. They are characterised by the fact that they have different electronic and magnetic properties at the surfaces and interfaces than in the volume.
Alexander Gray is a well-known expert in this field and frequently comes to BESSY II for short measurement periods, where he cooperates with Florian Kronast. As a Fellow of the Alexander von Humboldt Foundation, the American physicist can now finance regular guest stays at HZB with Florian Kronast's team and at Forschungszentrum Jülich with Claus Schneider's team. "The Humboldt Fellowship gives us more time, so we can investigate and discuss in more detail how the interplay between surface, interface and bulk properties in quantum materials leads to novel phenomena that enable device applications," he says.
Gray leads a team at Temple University in Philadelphia and also plans to send his students to BESSY II. "We want to develop new techniques to study the electronic and magnetic properties of 2D quantum materials and quantum devices in more detail," he outlines his goals. At BESSY II, Gray will primarily develop depth-resolved standing-wave photoemission microscopy further for this purpose. Kronast, Gray, and his former doctoral advisor Chuck Fadley have already combined this method with excitation by standing X-ray waves to enable depth resolution (SW-PEEM).
From mid-August, Alexander Gray is planning his first stay at BESSY II. He is not only looking forward to the measurements and many discussions, but also to the typical Berlin atmosphere: "The people are really open and friendly, and I have never experienced the famous "Berlin snout". I think if I do one day, I might deserve it." With this attitude, full of humor, his stay in Berlin will be a huge success in every aspect.
- Only at BESSY II worldwide: IR nanoscopy at very long THz wavelengthsThe team at the IRIS beamline at BESSY II has created a new experimental option: They achieved infrared nanoscopy with a spatial resolution of around 50 nm at very long THz wavelengths. This was possible thanks to a temporal pattern of light pulses known as the low-alpha operating mode at BESSY II. Worldwide, BESSY II is the only synchrotron light source at which users could perform nanoscopy in a single setup from 25 to 4000 cm-1, a unique opportunity for ultra-broadband characterisation of complex materials at the nanoscale in both the life sciences and materials sciences.
- Ultrafast demagnetisation - Thinner iron, stronger effectThe thinner an iron film, the more easily it can be demagnetised by a laser pulse. Researchers at the University of Duisburg-Essen, working with Helmholtz-Zentrum Berlin and other partners, have discovered why: the key lies in the magnetic order at the material's interfaces. In the long term, these findings could contribute to the development of new technologies for magnetic data storage. The results have been published in the scientific journal Advanced Science.
- Blind spot for the arrangement of atomsArtificial intelligence is increasingly being used to predict the properties of new materials. A research team from Jena and the United States now shows in a study published in the journal Nature Computational Science that when language models are used for this purpose, they reliably identify which types of atoms a material contains. However, they make insufficient use of information about how those atoms are arranged in space. Neither larger models nor additional training data resolve this weakness. For material properties that depend strongly on structure, AI models specifically designed to process spatial relationships are therefore the more reliable choice. (DOI: 10.1038/s43588-026-01045-2)