Trigonal PtBi Superconducting Weyl Semimetal: New Insights Into Electronic Properties From Hall And Nernst Effects

On April 18, 2025, researchers published Fermi surface evolution in Weyl semimetal t-PtBi probed by transverse transport properties, detailing how the Fermi surface evolves in t-PtBi using Hall and Nernst effects, revealing changes in electronic properties tied to hole-like pockets.

Trigonal PtBi, a type-I Weyl semimetal, exhibits superconductivity and non-trivial topology. Researchers investigated its electronic properties using Hall and Nernst effects on a single crystal, revealing a temperature- and magnetic field-dependent evolution of hole-like pockets in the Fermi Surface. This finding advances understanding of its complex band structure and potential for novel quantum devices.

Topological semimetals are materials where the conduction and valence bands touch at points or lines, leading to unique surface states protected by topology. These properties can result in phenomena such as the quantum spin Hall effect, which could revolutionize electronic devices by enabling dissipationless current flow.

The Nernst effect, observed in PtBi₂, involves a temperature gradient inducing an electric current perpendicular to both the gradient and a magnetic field. This effect is particularly pronounced in materials with strong spin-orbit coupling, which PtBi₂ exhibits due to its topological nature. The angular dependence of this effect suggests that the direction of the magnetic field significantly influences thermoelectric properties, indicating anisotropic electronic states.

Research has shown how PtBi₂’s Hall resistivity and Nernst coefficient vary with magnetic field and temperature. These variations highlight the material’s complex electronic behavior, suggesting contributions from both electrons and holes in conduction.

The Nernst coefficient varies with the angle of the magnetic field relative to the material’s structure. This angular dependence implies that the efficiency of heat-to-electricity conversion is direction-dependent, a critical factor for optimizing thermoelectric devices.

A Lifshitz transition in PtBi₂, where the Fermi surface topology changes with varying chemical potential, has been observed. Such transitions can lead to abrupt changes in material properties, potentially enhancing or altering its electronic behavior for specific applications.

PtBi₂’s unique properties position it as a promising candidate for spintronic devices and thermoelectric applications. The research underscores the importance of understanding how quantum phenomena can be harnessed for technological advancements. Further studies, particularly on strain engineering, could unlock new ways to tune these properties, offering exciting possibilities for future innovations.

In conclusion, PtBi₂ exemplifies the fascinating world of quantum materials, where fundamental discoveries can pave the way for transformative technologies. Its angular-dependent Nernst effect and dynamic Fermi surface provide a rich ground for exploration, promising insights into both basic physics and applied sciences.