Multiple Superconducting Transitions in {\alpha}-Sn Films Grown by Molecular Beam Epitaxy

TL;DR

This study investigates the superconducting properties of { extalpha}-Sn thin films grown by molecular beam epitaxy, revealing multiple superconducting transitions influenced by strain, aging, and phase composition, with implications for topological physics.

Contribution

It reports the observation of multiple superconducting transitions in { extalpha}-Sn films and explores how substrate, thickness, strain, and aging affect these properties, providing new insights into topological superconductor candidates.

Findings

Multiple superconducting transitions observed above 4.5 K.

Transitions are affected by strain and aging effects.

Possible identification of phase-related superconductivity around 3.7 K.

Abstract

Gray tin, also known as {\alpha}-Sn, has been attracting research interest recent years due to its topological nontrivial properties predicted theoretically. The Dirac linear band dispersion has been proved experimentally by angle resolved photoemission spectroscopy. We have grown a series of {\alpha}-Sn thin film samples in two types with different substrates and thicknesses by molecular beam epitaxy. To explore the possible exotic physical properties related to the topological band structures, we have measured the electrical transport properties of our {\alpha}-Sn thin film samples and observed multiple superconducting transitions. We have identified the transitions above 4.5 K, besides the transition maybe related to the \b{eta} phase around 3.7 K. The changes of the superconducting properties over time reflect the aging effects in our samples. We have also confirmed the strain effects on the superconducting transitions through altering the relative thickness of our samples.