Superconductor derived from a topological insulator heterostructure

Topological superconductors (TSCs) are of significant current interest because they offer promising platforms for finding Majorana fermions. Here we report on a superconductor synthesized by intercalating Cu into a naturally formed topological insulator (TI) heterostructure consisting of Bi₂Se₃ TI units separated by nontopological PbSe units. Interestingly, in this TI-based superconductor, the specific-heat behavior suggests the occurrence of unconventional superconductivity with gap nodes. The existence of gap nodes in a strongly spin-orbit coupled superconductor would give rise to spin-split Andreev bound states that are the hallmark of topological superconductivity. Hence, this superconductor emerges as an intriguing candidate TSC.