PtBi2 Superconductor Breaks Physics Rules
Researchers at IFW Dresden have discovered a new type of superconductor called PtBi2. This shiny gray crystal is unusual because only its outer surfaces become superconducting. Electrons on the surface pair up and flow without resistance, while the interior stays a normal metal. The discovery challenges known rules of superconductivity. Electrons on PtBi2’s surface pair in a six-fold pattern, unlike any previously observed. Additionally, the crystal’s edges naturally host Majorana particles, which are vital for quantum computing.
How PtBi2 Works
PtBi2’s behavior comes from its topological properties. Electrons are confined to the top and bottom surfaces due to the crystal’s atomic structure. This property is highly stable and remains unless the crystal is reshaped or exposed to strong fields. At low temperatures, surface electrons pair up to form superconductivity. The interior electrons, however, do not pair and act like ordinary metal. This creates a natural “superconductor sandwich” with superconducting surfaces and a normal interior. High-resolution measurements confirm that electrons in six specific directions on the surface do not pair. This unique pairing pattern reflects the crystal’s three-fold atomic symmetry. The crystal’s edges also trap Majorana particles, which are promising for fault-tolerant quantum bits. Researchers are exploring ways to control these effects.
Thinning the material or applying magnetic fields could guide Majoranas and enhance quantum computing applications. PtBi2 is now considered one of the most compelling examples of an intrinsic topological superconducter.
