This work was supported as part of the Center for Mesoscale
Transport Properties, an Energy Frontier Research Center
supported by the U.S. Department of Energy, Office of
Science, Basic Energy Sciences, under award #DE-SC0012673.
We also acknowledge support from DOE BES under award
#DE-SC0016082. This work made use of the Cornell Center
for Materials Research Shared Facilities which are supported
through the NSF MRSEC program (DMR-1719875). The
authors express their gratitude to Pengyu Chen and Ziang Gao
for valuable discussions.