How Spin Relaxes in Bulk Halide Perovskites

Spintronics in halide perovskites has drawn significant attention in recent years, due to highly tunable spin-orbit fields and intriguing interplay with lattice symmetry. Spin lifetime -- a key parameter that determines the applicability of materials for spintronics and spin-based quantum information applications -- has been extensively measured in halide perovskites, but not yet assessed from first-principles calculations. Here, we leverage our recently-developed ab initio density-matrix dynamics framework [1, 2] to compute the spin relaxation time T₁ and ensemble spin dephasing time T₂ in a prototype halide perovskite, namely CsPbBr₃ with self-consistent spin-orbit coupling and quantum descriptions of the electron scattering processes. We also implement the Lande g-factor for solids from first principles and take it into account in our dynamics, which is required to accurately capture spin dephasing under external magnetic fields. We thereby predict intrinsic spin lifetimes as an upper bound for experiments, identify the dominant spin relaxation pathways, and evaluate the dependence on temperature, external fields, carrier density, and impurities. Importantly, we find that the Fröhlich interaction that dominates carrier relaxation contributes negligibly to spin relaxation, consistent with the spin-conserving nature of this interaction. Our theoretical approach may lead to new strategies to optimize spin and carrier transport properties in spintronics and quantum information applications. [1] Xu et al., Nat. Commun., 11, 2780, (2020). [2] Xu et al., Phys. Rev. B, 104, 184418, (2021).