Newswise — Scientists have dedicated their efforts to studying topological materials, focusing on the shape, or topology, of their electronic structures. These materials exhibit unique properties that have the potential to be harnessed for next-generation devices, despite their invisible nature in real space.
Initially, it was believed that only crystalline materials, characterized by highly ordered atoms arranged in repeating patterns, could exhibit topological physical properties. Amorphous materials, in which atoms are disordered and arranged only periodically over short distances, were considered unsuitable for hosting such properties.
However, a collaborative research group led by Associate Professor Kohei Fujiwara and Professor Atsushi Tsukazaki from Tohoku University's Institute for Materials Research (IMR), along with Lecturer Yasuyuki Kato and Professor Yukitoshi Motome from the University of Tokyo's Graduate School of Engineering, and Associate Professor Hitoshi Abe from the High Energy Accelerator Research Organization's Institute for Materials Structure Science, has made a groundbreaking discovery. They have verified that even amorphous materials can possess these special properties.
The team's findings, published in the journal Nature Communications on June 13, 2023, reveal that the concept of band topology, previously discussed mainly in relation to crystals, is also applicable and technologically useful in amorphous states. "We discovered that the concept of band topology, which has been discussed mainly in crystals, is also valid and technologically useful in amorphous states," stated Fujiwara.
To validate their discovery, the researchers conducted experiments and model calculations on iron-tin amorphous thin films. They successfully demonstrated that, despite the short-range arrangement of atoms, the amorphous material exhibited the same exceptional effects as crystalline materials, including the anomalous Hall effect and the Nernst effect.
Fujiwara further explains the significance of their findings: "Amorphous materials are easier and cheaper to make compared to crystals, so this opens up new possibilities for developing devices using these materials. This could lead to advancements in sensing technology, which is important for creating the Internet of Things (IoT), where many devices are connected and communicate with each other."
Looking ahead, the research group aims to discover more amorphous materials and leverage them to develop innovative devices, thereby advancing the field of materials science.
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