Two-dimensional chiral perovskites with large spin Hall angle and collinear spin Hall conductivity

Abstract

Two-dimensional hybrid organic-inorganic perovskites with chiral spin texture are emergent spin-optoelectronic materials. Despite the wealth of chiro-optical studies on these materials, their charge-to-spin conversion efficiency is unknown. We demonstrate highly efficient electrically driven charge-to-spin conversion in enantiopure chiral perovskites (R/S-MB) 2 (MA) 3 Pb 4 I 13 (〈 n 〉 = 4), where MB is 2-methylbutylamine, MA is methylamine, Pb is lead, and I is iodine. Using scanning photovoltage microscopy, we measured a spin Hall angle θ sh of 5% and a spin lifetime of ~75 picoseconds at room temperature in 〈 n 〉 = 4 chiral perovskites, which is much larger than its racemic counterpart as well as the lower 〈 n 〉 homologs. In addition to current-induced transverse spin current, the presence of a coexisting out-of-plane spin current confirms that both conventional and collinear spin Hall conductivities exist in these low-dimensional crystals.