A team of researchers from the Cluster of Excellence ct.qmat based at the universities JMU Würzburg and TU Dresden has engineered the topological insulator manganese bismuth telluride (MnBi6Te10) to make it ferromagnetic. The amazing thing about this quantum material is that its ferromagnetic properties only occur when antisite disorder is introduced into its atomic structure. To achieve this, some manganese atoms (green) need to be relocated from their original position (second green atomic layer from the top). Only when manganese atoms are present in all the layers containing bismuth atoms (gray) does the magnetic interaction between them become sufficiently contagious to point them in the same direction and create ferromagnetism. Credit: Jörg Bandmann / ct.qmat
Magnetic topological insulators are an exotic class of materials that conduct electrons without any resistance at all and so are regarded as a promising breakthrough in materials science. Researchers from the Cluster of Excellence ct.qmat in Würzburg and Dresden have achieved a significant milestone in the pursuit of energy-efficient quantum technologies by designing the ferromagnetic topological insulator MnBi6Te10 from the manganese bismuth telluride family. The amazing thing about this quantum material is that its ferromagnetic properties only occur when some atoms swap places, introducing antisite disorder. The findings have been published in the journal Advanced Science.
Harbingers of new technology
In 2019, an international research team headed by materials chemist Anna Isaeva, at that time a junior professor at ct.qmat – Complexity and Topology in Quantum Matter, caused a stir by fabricating the world’s first antiferromagnetic topological insulator – manganese bismuth telluride (MnBi2Te4). This remarkable material has its own internal magnetic field, paving the way for new kinds of electronic components that can store information magnetically and transport it on the surface without any resistance. This could revolutionize computers by making them more sustainable and energy-efficient. Since then, researchers around the globe have been actively studying various aspects of this promising quantum material, eager to unlock its full potential.
Milestone achieved with MnBi6Te10
Based on the previously discovered MnBi2Te4, a team from ct.qmat has now engineered a topological insulator with ferromagnetic properties known as MnBi6Te10. In ferromagnetic materials, the individual manganese atoms are magnetically aligned in parallel, meaning that all their magnetic moments point in the same direction. By contrast, in its antiferromagnetic predecessor, MnBi2Te4, only the magnetic moments within a single layer of the material are aligned in this way. The slight change in the crystal’s chemical composition has a major impact, as the ferromagnetic topological insulator MnBi6Te10 exhibits a stronger and more robust magnetic field than its antiferromagnetic predecessor. “We managed to fabricate the quantum material MnBi6Te10 such that it becomes ferromagnetic at 12 Kelvin. Although this temperature of –261 degrees DOI: 10.1002/advs.202203239
Cluster of Excellence ct.qmat
The Cluster of Excellence ct.qmat – Complexity and Topology in Quantum Matter has been jointly run by Julius-Maximilians-Universität Würzburg and Technische Universität Dresden since 2019. Nearly 400 scientists from more than 30 countries and from four continents study topological quantum materials that reveal surprising phenomena under extreme conditions such as ultra-low temperatures, high pressure, or strong magnetic fields. ct.qmat is funded through the German Excellence Strategy of the Federal and State Governments and is the only Cluster of Excellence to be based in two different federal states.
