Spin dynamics in lead-halide perovskites

Nataliia Kopteva^a, Dmitri Yakovlev^a, Eyüp Yalcin^a, Ina Kalitukha^a, Ilya Akimov^a, Mikhail Nestoklon^a, Bekir Turedi^b^,^c, Oleh Hordiichuk^b^,^c, Dmitry Dirin^b^,^c, Maksym Kovalenko^b^,^c, Manfred Bayer^b^,^c

^aExperimental Physics 2, TU Dortmund University, 44227 Dortmund, Germany

^bETH Zurich, Laboratory of Inorganic Chemistry, Department of Chemistry & Applied Biosciences, Vladimir-Prelog-Weg, 1, Zürich, Switzerland

^cLaboratory for Thin Films and Photovoltaics Empa-Swiss Federal Laboratories for Materials Science and Technology Dübendorf CH-8600, Switzerland

Proceedings of Perovskite Semiconductors: From Fundamental Properties to Devices (PerFunPro)

Konstanz, Germany, 2025 September 8th - 10th

Organizers: Lukas Schmidt-Mende, Vladimir Dyakonov and Selina Olthof

Invited Speaker, Nataliia Kopteva, presentation 005
Publication date: 16th July 2025

Lead halide perovskites represent a versatile platform for studying spin phenomena in semiconductors, owing to their tunable crystal symmetry, strong spin–orbit coupling, and long spin lifetimes [1]. We overview our experimental studies of spin dependent properties and spin dynamics in the perovskite crystals and nanocrystals. We investigate exciton and carrier spin polarization at cryogenic temperatures in bulk perovskite crystals with near-cubic (FA₀.₉Cs₀.₁PbI₂.₈Br₀.₂, FAPbBr₃) and orthorhombic (MAPbI₃, CsPbBr₃) symmetries. A high degree of optical orientation up to 85% is observed, indicating strong spin selectivity and efficient spin initialization under circularly polarized excitation [2,3,4].

In FA₀.₉Cs₀.₁PbI₂.₈Br₀.₂, we explore the spin orientation of localized electrons and holes using polarized photoluminescence and time-resolved differential reflectivity. At 1.6 K, continuous-wave excitation yields optical orientation degrees of 6% and 2% for electrons and holes, respectively. These contributions are clearly distinguished from excitonic signals by analyzing the Hanle effect in transverse magnetic fields and the polarization recovery effect in longitudinal fields [5].

The spin orientation remains stable to excitation energy detunings up to 0.25 eV and decreases gradually up to 0.9 eV, indicating inefficient spin relaxation during carrier energy relaxation. Across all studied symmetries, the absence of spin relaxation acceleration suggests suppression of the Dyakonov–Perel mechanism and no evidence of Dresselhaus–Rashba spin splitting, implying preserved spatial inversion symmetry. Coherent spin quantum beats and electron-hole spin correlations further support these conclusions [2].

Even with additional symmetry reduction in CsPbI₃ nanocrystals due to spatial confinement [6], spin relaxation mechanisms associated with inversion symmetry breaking are not activated. Instead, exciton spin polarization is primarily governed by exchange interactions within the exciton.

Furthermore, spin relaxation of localized carriers is driven by hyperfine interactions with nuclear spins. Dynamic nuclear spin polarization is observed, with Overhauser fields reaching +4 mT for electrons and −76 mT for holes [5]. This pronounced asymmetry highlights a unique characteristic of lead halide perovskites, where hole–nuclear spin coupling significantly exceeds that of electrons, in a contrast to most conventional semiconductors.

These findings demonstrate the intrinsic robustness of spin polarization and coherence in lead halide perovskites. Their ability to maintain spin orientation under structural and energetic perturbations makes them highly promising candidates for spintronic applications, where optical control and long spin lifetimes are essential.

References:

[1] Organic Inorganic Perovskites: Physical Properties and Applications. (eds. Z. V. Vardeny and M. C. Beard) (World Scientific,2022).

[2] Kopteva, N. E.; et al., Highly-polarized emission provided by giant optical orientation of exciton spins in lead halide perovskite crystals, Advanced Science, 2024, 11, 2403691

[3] Kopteva, N. E.; et al., Optical orientation of excitons and charge carriers in methylammonium lead iodide perovskite single crystals in the orthorhombic phase, Phys. Rev. B, 2025, 111, 195201.

[4] Kopteva, N. E.; et al., Effect of crystal symmetry of lead halide perovskites on the optical orientation of excitons, Advanced Science, 2025, 12, 2416782.

[5] Kudlacik, D.; Kopteva, N. E.; et al., Optical spin orientation of localized electrons and holes interacting with nuclei in a FA0.9Cs0.1PbI2.8Br0.2 perovskite crystal. ACS Photonics, 2024, 11, 2757.

[6] Kirstein, E.; Kopteva, N. E.; et al., Mode locking of hole spin coherences in CsPb(Cl,Br)3 perovskite nanocrystals, Nature Comm., 2023, 14, 699.

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