Scientists from the Cluster of Excellence ct.qmat—Complexity and Topology in Quantum Matter have developed a new understanding of how electrons behave in strong magnetic fields. Their results explain measurements of electric currents in three-dimensional materials that signal a quantum Hall effect—a phenomenon thus far only associated with two-dimensional metals. This new 3D effect can be the foundation for topological quantum phenomena, which are believed to be particularly robust and therefore promising candidates for extremely powerful quantum technologies. These results have just been published in the scientific journal Nature Communications.