The subject of this dissertation is the experimental study of quantum coherent transport phenomena in epitaxial single-crystal halide perovskite thin films. The experiments consist of low-temperature (down to 10 mK) magnetotransport measurements at high magnetic field (up to 14 T).The recent advent of epitaxial thin film growth of inorganic halide perovskites has made it possible to investigate the quantum behavior of charge carriers in these materials in low-dimensional form. We present results on epitaxial single-domain cesium tin iodide (CsSnI3) thin films that clearly demonstrate quantum transport in this material for the first time. The observed low-field magnetoresistance shows signatures of weak anti-localization (WAL) that reveals coherent quantum interference effects and spin-orbit coupling. A micron-scale (≈5 um) low-temperature phase coherence length for charge carriers in the system is extracted from these WAL measurements.Additionally, we present low-temperature quantum magnetotransport measurements on thin film devices made of epitaxial single-crystal CsSnBr3, which exhibit two-dimensional Mott variable range hopping (VRH) and a large negative magnetoresistance. These findings are described by the Nguyen-Spivak-Shkovskii (NSS) model for quantum interference between different directed hopping paths, and we extract the temperature-dependent hopping length of charge carriers, their localization length, and a lower bound for their phase coherence length of ~100 nm at low temperatures. These results from CsSnI3 and CsSnBr3 devices demonstrate that epitaxial halide perovskite devices are emerging as a material class for low-dimensional quantum coherent transport devices.In addition to the works that are described above, I have also been involved in several additional projects, such as experiments on low-dimensional electron systems and superconducting qubit experiments, which will not be described in this dissertation.
Read
