Topology Revealed by Dissipationless Charge Transport in Platinum-Bismuth

Overview

An international research team, including scientists from the IFW Dresden and the Würzburg-Dresden Cluster of Excellence ct.qmat, has discovered a new transport phenomenon in the material platinum-bismuth (PtBi₂). For the first time, the researchers detected a clear signal of dissipationless charge transport in a so-called topological nodal-line semimetal. This finding establishes a new signature of the topological nature of such materials and opens up important perspectives for future applications of topological properties. The results were published in Nature Communications in July 2025.

Room-temperature-stable transversal signal in PtBi₂

At the heart of the study lies the material platinum-bismuth (PtBi₂), a topological semimetal known for its unusual electronic properties. A particular feature of PtBi₂ are so-called topological nodal lines, which until now had not been detected through charge transport measurements.

The team has now demonstrated that even extremely small magnetic fields can deliberately alter the special electronic structure of PtBi₂. In this process, the nodal lines transform into Weyl points. This topological transformation generates an electromagnetic signal within the quantum structure of the crystal, which can be directly measured using standard transport techniques.

In addition, the researchers observed a previously unknown angular dependence: when an electrical current flows through the material under the influence of a magnetic field, the lateral resistance changes in a very specific way depending on the angle of the field. Importantly, this effect occurs without any dissipation and remains stable up to room temperature – in contrast to many other quantum phenomena, which usually require extremely low temperatures.

Significance for research methods and future technologies

This discovery not only provides a new method to investigate the special topology of such materials but also offers a path to actively control it. As a result, PtBi₂ and similar materials are promising candidates for next-generation technologies.