Magneto-optical studies of hybrid organic/inorganic perovskite: The case of methyl-ammonium lead bromide

Picosecond time-resolved and cw magneto-optical methods have been used for studying the spin-related properties of excitons and photocarriers in methyl-ammonium lead bromide (${\mathrm{MAPbBr}}_{3}$) thin film, single crystal, and light-emitting diodes (LED), focusing on the Land\'e $g$ values of these species. Using the transient circularly polarized photoinduced quantum beatings (QB) under an applied magnetic field, B in ${\mathrm{MAPbBr}}_{3}$ single crystal, we obtained the anisotropic $g$ values of electrons for B field along [010] and [001]: $|{g}_{[001]}^{\mathrm{e}}|=2.15$ and $|{g}_{[010]}^{\mathrm{e}}|=1.75$, and for holes $|{g}_{[001]}^{\mathrm{h}}|=0.42$ and $|{g}_{[010]}^{\mathrm{h}}|=0.60$. We also used the magnetic circular dichroism method for measuring the bright excitons' $g$ value, ${g}_{\mathrm{ex}}={g}_{\mathrm{e}}+{g}_{\mathrm{h}}=2.5$. From these two types of measurements we conclude that ${g}_{\mathrm{h}}>0$ in ${\mathrm{MAPbBr}}_{3}$. This conclusion was corroborated by measuring the magnetoelectroluminescence response of LED based on ${\mathrm{MAPbBr}}_{3}$ active layer. The $g$ values in single crystal and their average in films are in excellent agreement with a k\ifmmode\cdot\else\textperiodcentered\fi{}p model that shows similarity and difference to those of ${\mathrm{MAPbI}}_{3}$. We also observed the influence of the Overhauser field on the QB frequencies that is induced by the dynamic nuclear polarization generated by the spin-aligned electrons using circularly polarized pump or probe beams.