arXiv subjects

David H. Yi

Publications and source records attributed to David H. Yi.

2 recordsLinked to original sources

arXiv2026

Superconducting PdTe Thin Film Via Topotactic Transformation, Toward Topological Superconductors

Topological superconductors (TSCs) hosting Majorana zero modes (MZMs) offer a pathway to fault-tolerant quantum computation. PdTe is a promising TSC candidate due to its topological surface states and a reasonable superconducting critical temperature of ~4.5 K. However, it has been challenging to grow PdTe thin films with bulk-like superconducting properties. Here, we show that high-quality, superconducting PdTe thin films can be grown using molecular beam epitaxy (MBE). The films exhibit a sharp superconducting transition (T_onset = 4.43 K with transition width of 0.06 K), comparable to that of bulk crystals. This was made possible via a topotactic transformation from a PdTe_2 buffer layer to a PdTe phase by growing Pd on top under Te-deficient conditions. Structural and transport analyses confirm the NiAs-type structure of PdTe, as well as its two-dimensional superconducting behavior and excellent air stability. These findings suggest that the MBE-grown PdTe films and their heterostructures are a promising platform for topological superconductivity and Majorana physics.

cond-mat.supr-con↗

arXiv2024

Single-domain imaging in topological insulator Bi2Te3 thin films

Single crystalline materials, different from polycrystalline and twinning structures, are desired for investigating the intrinsic physical properties, as grain and twin boundaries often work as a source of artifacts. Bismuth chalcogenides, which are van der Waals materials notable as topological insulators, have attracted significant interest due to their rich physical properties. However, the formation of 60° twin domains is common in these materials. Here, we demonstrate single-domain bismuth chalcogenides. Using atomic force microscopy, we investigated the morphology of Bi2Se3 and Bi2Te3 grown on Al2O3. Despite lattice constants of Bi2Se3 and Al2O3 substrates being well matched with hybrid symmetry epitaxy, Bi2Se3 exhibited 60° twin boundaries across the surface. Interestingly, Bi2Te3 showed a single-domain feature across the 10 mm by 10 mm sample even with lattice mismatch. While further in-depth studies are required to understand this difference in the morphology between Bi2Se3/Al2O3 and Bi2Te3/Al2O3, we suggest that the formation of twin boundaries in bismuth chalcogenides is related to the interaction between quintuple layers across the van der Waals gap rather than strain or defects.

cond-mat.mtrl-sci↗