Extraordinary Phase Coherence Length in Epitaxial Halide Perovskites*

Inorganic halide perovskites have emerged as a promising platform for a wide range of applications from solar energy harvesting to computing. With the recent advent of epitaxial thin film growth of halide perovskites it is now possible, for the first time, to investigate low-dimensional quantum electronic devices based on these materials. We leverage advances in vapor-phase epitaxy of halide perovskites to perform low-temperature quantum electrical and magnetotransport measurements on single-domain cesium tin iodide (CsSnI₃) epitaxial thin film devices. The low field magnetoresistance carries signatures of coherent quantum interference effects and spin-orbit coupling. We find that the low-temperature phase coherence length for charge carriers in this material exceeds that reported in two-dimensional electron systems in silicon, gallium arsenide, and graphene. These results open the door to epitaxial halide perovskite heterostructures for investigating and exploiting coherent quantum electronic effects for applications in spintronics and spin-orbitronics.