Electrical Transport Study in α-Sn Films Grown by Molecular Beam Epitaxy

Alpha tin (α-Sn) is an allotrope of tin with a diamond crystal structure, and has been predicted to become topologically nontrivial by applying uniaxial strain. While the topological band structures have been confirmed by angle-resolved photoemission spectroscopy (ARPES), however, the transport properties of α-Sn still need thorough investigations.
We have grown a series of α-Sn films with different thicknesses on InSb and CdTe substrates, respectively, by molecular beam epitaxy (MBE). The high quality has been confirmed by structural characterizations such as X-ray diffraction and transmission electron microscope. The temperature- and thickness-dependent electrical transport of the α-Sn films have been investigated. A large magnetoresistance (MR) has been observed in the α-Sn/InSb heterostructures, up to over 450,000% at 1.5 K and 14 T. On the other hand, multiple transitions in transport type have been observed in the α-Sn films grown on CdTe substrates, which can be well explained by a three-band model. We have established a phase diagram illustrating the transport behaviors of α-Sn. These results can give more insights into the transport mechanism and potential applications of this material system.