Rapid spin depolarization in the layered 2D Ruddlesden Popper perovskite (BA)(MA)PbI

TL;DR

This study investigates spin dynamics in a layered 2D perovskite, revealing rapid spin dephasing that limits potential spintronic applications, despite stable exciton recombination lifetimes.

Contribution

It provides the first detailed measurement of spin dephasing times in 2D Ruddlesden-Popper perovskites, highlighting the ultrafast spin depolarization process.

Findings

Spin dephasing occurs on the order of picoseconds.

Exciton recombination lifetime is on the order of nanoseconds.

Spin polarization is absent in steady-state photoluminescence.

Abstract

We report temperature-dependent spectroscopy on the layered (n=4) two-dimensional (2D) Ruddlesden-Popper perovskite (BA)(MA)PbI. Helicity-resolved steady-state photoluminescence (PL) reveals no optical degree of polarization. Time-resolved PL shows a photocarrier lifetime on the order of nanoseconds. From simultaneaously recorded time-resolved differential reflectivity (TR$\Delta$R) and time-resolved Kerr ellipticity (TRKE), a photocarrier lifetime of a few nanoseconds and a spin dephasing time on the order of picoseconds was found. This stark contrast in lifetimes clearly explains the lack of spin polarization in steady-state PL. While we observe clear temperature-dependent effects on the PL dynamics that can be related to structural dynamics, the spin dephasing is nearly T-independent. Our results highlight that spin dephasing in 2D (BA)(MA)PbI occurs at time scales faster than the exciton recombination time, which poses a bottleneck for applications aimingto utilize this degree of freedom.