Optimization of Chiral 2D Perovskite (MBA)2PBI4 Devices for Low Temperature Magnetotransport Characterization*

We investigate chirality-dependent charge transport in the two-dimensional chiral hybrid perovskite (MBA)₂PbI₄ as a scalable, semiconducting platform to probe the chirality-induced spin selectivity (CISS). We fabricate micron-scale Hall bars on Si/SiO₂ with Ti/Au contacts and an Al back gate, optimize spin-coated films, and confirmed the chiral structure by out-of-plane XRD. SEM shows uniform coverage with micron-scale grains. Using a cryogenic magnet system, we measure longitudinal and Hall responses from 290 K down to 50 K in perpendicular fields up to 12 T.

The longitudinal resistance Rₓₓ displays two regimes: a mega-ohm regime at high temperature with an effective room-temperature resistivity ≈1.7×10³ Ω·cm (for ~100 nm thickness), followed by a sharp upturn below ~70 K into the giga-ohm range, consistent with carrier freeze-out. Hall and Magnetoresistance measurements were also performed down to low temperatures. Through these optimization steps, we have been able to both develop a platform for optimizing low temperature transport probing in (MBA)₂PbI₄, and generate initial resistivity, magnetoresistance, and hall measurements as a function of temperature.