Topological phase transitions in thin layers of alpha Sn

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We present results of our research on the MBE growth and investigation of topological characteristics of alpha Sn (α-Sn). Theory on the effects of quantum confinement, strain and orientation on the topological characteristics of α-Sn/InSb and α-Sn/CdTe quantum wells, predicted topological phase changes and the observation of Dirac semimetal behavior in magnetotransport measurements of thin layers of α-Sn will be discussed. Our theory shows onset of 3D and 2D Dirac semimetal phase in α-Sn/InSb(001) as a function of α-Sn film thickness and shows how α-Sn/InSb thin films retain gapless Dirac surface states down to ~50 anstrom thickness, despite hybridization scale of ~ 110 anngstrom. We find that orientation has a large impact on thickness dependent phase transitions in α-Sn/CdTe thin films.