Spin dynamics of electrons and holes interacting with nuclei in MAPbI$_3$ perovskite single crystals

TL;DR

This study investigates the spin dynamics of electrons and holes in MAPbI$_3$ perovskite single crystals using time-resolved Kerr rotation, revealing long spin relaxation times, anisotropic $g$-factors, and dynamic nuclear polarization effects at cryogenic temperatures.

Contribution

It provides detailed measurements of spin dephasing, relaxation, and $g$-factor anisotropy in MAPbI$_3$, and demonstrates nuclear polarization and carrier-nuclei interactions in this material.

Findings

Spin dephasing times up to a few nanoseconds.

Longitudinal spin relaxation time of 37 ns.

Carrier-nuclei interaction with nuclear spin relaxation exceeding 16 minutes.

Abstract

Methylammonium lead triiodine (MAPbI$_3$) is a material representative of the hybrid organic-inorganic lead halide perovskites which attract currently great attention due to their photovoltaic efficiency and bright optoelectronic properties. Here, the coherent spin dynamics of charge carriers and spin dependent phenomena induced by the carrier interaction with nuclear spins are studied in MAPbI$_3$ single crystals, using time-resolved Kerr rotation at cryogenic temperatures in magnetic fields up to 3 T. Spin dephasing times up to a few nanoseconds and a longitudinal spin relaxation time of 37 ns are measured. The Larmor spin precession of both resident electrons and holes is identified in the Kerr rotation signals. The Land\'e factors ($g$-factors) in the orthorhombic crystal phase show a strong anisotropy, ranging for the holes from $-0.28$ to $-0.71$ and for the electrons from $+2.46$ to $+2.98$, while the $g$-factor dispersion of about 1% is rather small. An exciton $g$-factor of $+2.3$ is measured by magneto-reflectivity. A dynamic nuclear polarization by means of spin polarized electrons and holes is achieved in tilted magnetic fields giving access to the carrier-nuclei exchange interaction and the nuclei spin relaxation time exceeding 16 minutes.