Layer-dependent Land\'e $g$-factors of electrons, holes, and excitons in two-dimensional Ruddlesden-Popper lead halide perovskites

TL;DR

This study measures and analyzes the layer-dependent Landé g-factors of electrons, holes, and excitons in 2D Ruddlesden-Popper lead halide perovskites, revealing confinement effects and deviations from bulk behavior.

Contribution

It provides the first systematic experimental and theoretical investigation of g-factors in 2D lead halide perovskites across different layer thicknesses.

Findings

Electron and hole g-factors evolve with layer thickness, deviating from bulk trends.

Experimental results align qualitatively with tight-binding calculations.

Exciton g-factors are determined up to 55 T magnetic field.

Abstract

Two-dimensional Ruddlesden-Popper lead halide perovskites provide a valuable platform for tailoring charge and spin properties through quantum confinement and reduced symmetry. While the electron and hole Land\'e $g$-factors in bulk lead halide perovskites exhibit a universal dependence on the band gap energy, their evolution in two-dimensional perovskites has remained largely unexplored. Here, the Zeeman splittings of electrons and holes in (PEA)$_2$MA$_{n-1}$Pb$_n$I$_{3n+1}$ perovskites with the number of inorganic layers ovarying in the range $n=1,...,8$ are measured by means of the spin-flip Raman scattering and time-resolved Kerr rotation magneto-optical techniques. A systematic evolution of the electron and hole $g$-factors with decreasing layer thickness, which deviates from the universal bulk behavior and reveals confinement-driven trends similar to those observed in perovskite nanocrystals, is found. The experimental results are in good qualitative agreement with empirical tight-binding calculations. The exciton $g$-factors are evaluated from the Zeeman splittings of the exciton resonances in reflectivity measured in pulsed magnetic fields up to 55~T. These results provide comprehensive insight into the spin properties of two-dimensional lead halide perovskites and establish them as a tunable platform for engineering spin-dependent phenomena in quantum-confined semiconductors.