Magneto-Optical Properties of Methylammonium Lead Iodide Perovskite Thin Films in the Orthorhombic domain

Hybrid lead halide perovskites have opened a new era for photovoltaics research over the last decade due to their high energy conversion energy. These materials are promising for future electronics and optoelectronics and applications in spin-electronic devices due to their unique properties, such as high coherent emission, spin-orbit coupling, and strong light-matter interaction [1]. Recent experimental and theoretical studies have shown that the polar organic cations affect the lattice polarization, giving rise to a ferroelectric behavior and enhancing their photovoltaic performance [2]. Furthermore, magnetism in halide perovskite at room temperature has been confirmed, suggesting a route toward spintronics applications based on magneto-optical perovskites [3-4]. However, the hybrid perovskites' magnetic properties are not well understood. Our work reports magneto-photoluminescence (MPL) and magneto-Raman (MR) measurements of methylammonium lead iodide CH₃NH₃PbI₃ (MAPbI₃) ~ 280 nm thin film materials at low temperatures (<60 K), where the crystalline structure is in the orthorhombic domain. We obtained different MPL spectra from random spots on the sample surface and fitted them with gaussian curves at 55 K and 1.6 K. The MPL spectra confirm the existence of a dual emission peak at a low temperature, consistent with previous works [5]. For each spot, we applied a magnetic field up to 9T in the perpendicular direction of the surface and analyzed the MPL plots as a function of the external magnetic field. Changes in the intensity, the central position, and the FWHM of the gaussian components were observed in the MPL spectra. We also compare the response of the thin film at room temperature (tetragonal domain) under the external magnetic field to the low temperature data.

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