Weak antilocalization in topological crystalline insulator SnTe films deposited using amorphous seeding on SrTiO3

Abstract

Topological crystalline insulators (TCIs) promise spin-polarized or dissipationless transport, which can be controlled by crystal symmetry breaking through applied strain or electric field. To realize TCI devices with gate-controlled topological states, it is necessary to develop methods for depositing continuous and thin TCI films on substrates suitable for electric-field gating. Here, we present an optimized templating procedure for depositing single-orientation, continuous films of TCI SnTe on SrTiO3, which is an oxide with a wide bandgap and large dielectric constant suitable for gated devices. This process takes advantage of a thin SnTe template layer crystallized after amorphous deposition, with additional SnTe being grown by molecular beam epitaxy and monitored with in situ laser ellipsometry. Continuous, single-phase SnTe films with a (001) orientation relative to the SrTiO3 lattice are achieved. Magnetoconductivity measurements of SnTe films reveal a coexistence of weak antilocalization, consistent with topologically non-trivial states, and weak localization, consistent with trivial states from the bulk. This method of analysis may be suitable to analyze the magnetotransport characteristics of any topological material with carriers in both topological and trivial bulk states. The maximum phase coherence length is achieved for films thicker than 20 unit cells, which could be used for gated-SnTe devices.