Magneto-optical study on excitonic spectra in (C6H13NH3)2PbI4

Abstract

Magnetoabsorption spectra of the lowest-energy excitons in a layered perovskite-type material (${\mathrm{C}}_6$ ${\mathrm{H}}_{21}$ ${\mathrm{NH}}_3$ ${)}_2$ ${\mathrm{PbI}}_4$ have been measured under pulsed high magnetic fields up to 42 T at 4.2 K in the Faraday configuration (E⊥c∥B) and the Voigt configuration (E⊥c⊥B). Energy shifts and splittings in the spectra for the Voigt configuration have been observed in this material. For the Faraday configuration, the Zeeman splitting with small diamagnetic shifts has clearly been detected. The diamagnetic coefficients obtained are much smaller than that for ${\mathrm{PbI}}_2$, suggesting that the Wannier-exciton model is not a good approximation for the lowest-energy excitons in (${\mathrm{C}}_6$ ${\mathrm{H}}_{13}$ ${\mathrm{NH}}_3$ ${)}_2$ ${\mathrm{PbI}}_4$. Theoretical analysis based on the cationic Frenkel-exciton model yields semiquantitative agreement with the experimental results.