Superconducting PdTe thin film via a Topotactic transformation process: Towards topological superconductors

Topological superconductors (TSC) hosting Majorana Zero Modes (MZM) have garnered significant attention due to their potential applications in quantum computing. TSCs can be realized by coupling superconductivity with a topological surface state. Three pathways toward achieving TSC states are discovering intrinsic topological superconductors, such as an unconventional superconductor, UTe₂, and engineering the proximity effect that combines superconductors (SC) with topological states in a heterostructure form. PdTe has recently emerged as a promising candidate because it exhibits both superconductivity below 4.5 K and topological surface states with Fermi arcs. Moreover, in the context of heterostructures, its hexagonal crystal structure and in-plane lattice constant (0.414 nm) closely matched those of a topological insulator, Bi₂Se₃, and an altermagnet, MnTe. All these properties make PdTe an ideal platform for realizing TSCs, either intrinsically or in heterostructures.

Here, we report the first successful synthesis of high-quality, centimeter-sized PdTe thin films grown by Molecular Beam Epitaxy (MBE). Transport measurements exhibit a high onset temperature (T_onset = 4.43 K), accompanied by a residual resistivity ratio (RRR) of 10. In situ Reflection High Energy Electron Diffraction (RHEED), ex situ X-ray Diffraction (XRD), low temperature electric transport measurements, and Scanning Transmission Electron Microscopy (STEM) confirm the high crystallinity with bulk-like T_c. We will discuss the growth mechanism and the results of the comprehensive characterization in detail.