Future Information Technologies: Germanium telluride's hidden properties at the nanoscale revealed
The Fermi surface of multidomain GeTe (111) bulk single crystal measured with high-resolution angle-resolved photoemission at BESSY II. © HZB
Germanium Telluride is an interesting candidate material for spintronic devices. In a comprehensive study at BESSY II, a Helmholtz-RSF Joint Research Group has now revealed how the spin texture switches by ferroelectric polarization within individual nanodomains.
Germanium telluride (GeTe) is known as a ferrolectric Rashba semiconductor with a number of interesting properties. The crystals consist of nanodomains, whose ferrolectric polarization can be switched by external electric fields. Because of the so-called Rashba effect, this ferroelectricity can also be used to switch electron spins within each domain. Germanium telluride is therefore an interesting material for spintronic devices, which allow data processing with significantly less energy input.
Russian German Cooperation
Now a team from HZB and the Lomonosov Moscow State University, which has established a Helmholtz-RSF Joint Research Group, has provided comprehensive insights into this material at the nanoscale. The group is headed by physical chemist Dr. Lada Yashina (Lomonosov State University) and HZB physicist Dr. Jaime Sánchez-Barriga. "We have examined the material using a variety of state-of-the-art methods to not only determine its atomic structure, but also the internal correlation between its atomic and electronic structure at the nanoscale," says Lada Yashina, who produced the high-quality crystalline samples in her laboratory.
Nanodomains observed in detail
Their microscopy investigations showed that the crystals possess two distinct types of boundaries surrounding ferroelectric nanodomains with sizes between 10 to 100 nanometres. At BESSY II, the team was able to observe two surface terminations with opposite ferroelectric polarization, and to analyse how these terminations correspond to nanodomains with either Ge or Te atoms at the topmost surface layer.
Ferroelectric polarization and spin texture
"At BESSY II, we were able to precisely analyze the intrincate relationship between the spin polarization in the bulk or at the surface and the opposite configurations of the ferroelectric polarization”, explains Jaime Sánchez-Barriga. The scientists also determined how the spin texture switches by ferroelectric polarization within individual nanodomains. "Our results are important for potential applications of ferroelectric Rashba semiconductors in non-volatile spintronic devices with extended memory and computing capabilities at the nanoscale," emphasizes Sánchez-Barriga.
- 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)
- Patterns of polar vortices in lead-free superlattices on siliconA team at HZB has, for the first time, reported polar vortices in (BaTiO3/SrTiO3)10 superlattices on silicon. These results expand the range of materials and substrates on which polar topological textures can occur and open up new options for incorporating complex ferroelectric states into silicon-based technologies.
- HZB congratulates Peter Hegemann on winning the Nobel PrizeOur warmest congratulations go to Peter Hegemann, Professor of Neuroscience and Experimental Biophysics at Humboldt University in Berlin. Together with Prof. Georg Nagel (Julius Maximilian University of Würzburg) and Prof. Karl Deisseroth (Stanford University, USA), he has been awarded the 2026 Nobel Prize in Physiology or Medicine. We are delighted for him, his team, Humboldt University and the entire Berlin scientific community.