thin films*

Originally of interest for its resistivity anomaly, ZrTe₅ has been predicted by recent theoretical work to be a quantum spin Hall insulator (QSHI) with band-gap of ~100meV [PRX 4, 011002 (2014)]. Additionally, bulk measurements of ZrTe₅ have shown a variety of states from a strong topological insulator (TI) to a weak TI and even a Dirac Semimetal depending on the experimental methods [Scientific Reports 7, 45667 (2017)]. This makes ZrTe₅ also interesting for studying the transition from a weak to strong TI. Since experiments so far have used films exfoliated from bulk crystals, they are complicated by the difficulty of exfoliating large area crystals. Moreover, rapid oxidization of ZrTe₅ films prevents thorough analysis of exfoliated thin films. To help elucidate the nature of the topological properties of ZrTe₅ and achieve a large band-gap QSHI, we have grown epitaxial thin films under ultra-high vacuum using molecular beam epitaxy (MBE) and performed in-vacuo analysis using ARPES and STM to confirm the growth quality and analyze the band structure, laying the groundwork for future MBE studies that utilize strain engineering to study the strong to weak TI transition and the observation of a large gap QSHI.