Control of the Structural Phases of Tin (Sn) thin films Through Lattice Engineering

Topology and superconductivity, two distinct but potentially interconnected phenomena offer unique insight into quantum properties and their applications in quantum technologies, spintronics, and sustainable energy technologies. Tin (Sn) plays a pivotal role here as an element due to its two structural phases, α-Sn and β-Sn, exhibiting topological behavior and superconductivity, respectively. This study explores precise control of α- and β-Sn phases in Sn thin films using molecular beam epitaxy through a systematic variation of the lattice constant. The crystal structure of the Sn films was characterized by x-ray diffraction, revealing the presence of α- or β-Sn phases, and confirmed by scanning transmission electron microscopy. The smooth and continuous surface morphology of the Sn films was validated using atomic force microscopy. The presence of α- or β-Sn phases were further verified using electrical transport measurements. Observed quantum oscillations and negative magnetoresistance are consistent with the topological nature of the α-Sn phase. Resistance drop near 3.7 K indicates the presence of superconductivity of the β-Sn phase. This study sheds light on controlling Sn phases through lattice engineering, enabling innovative applications in quantum technologies and beyond.