Spin-Optotronic Properties of Solids from Ab-Initio Density-Matrix Dynamics

<i>Ab initio</i> spin dynamics and transport simulations are critical for predicting new materials and realizing the potential of spintronics, spin-based quantum information science, and spin-selective photo-chemistry. In particular, simulations would be invaluable to predict key physical parameters including spin lifetime, spin diffusion and coherence length, magneto-optical spectra, and (spin)-photocurrent.<br/><br/>In this talk we will introduce our recently developed real-time density-matrix dynamics approach with first-principles electron-electron, electron-phonon, electron-impurity scatterings and self-consistent spin-orbit coupling, which can accurately predict spin and carrier lifetime, spin diffusion length, and pump-probe Kerr-rotation signatures for general solids, with examples of Si, GaAs, 2D materials, and halide perovskites[1-5]. We will show recent study of how <i>g</i> factor fluctuations lead to spin dephasing in halide perovskites under external magnetic field and their distinct electron-phonon contribution to spin and carrier relaxations[6]. We next will introduce our recent progress of developing methodology for spin-optotronic signatures, such as circular dichroism and circular/spin photogalvanic effect to chiral and broken-inversion-symmetry solids[7]. Importantly, with our real-time density matrix dynamics, we can explicitly include excitation, scattering, simulated and spontaneous emission processes from ab-initio calculations, at presence of electron-electron, electron-phonon, electron-impurity interactions. Such formalism describes complete kinetic processes and can be potentially applied to computing various transient and steady-state photocurrents or nonlinear optics[4].<br/>[1] “A universal spin relaxation model in solids” APS Physics Magazine, 2021. J. Xu, Y. Ping, PRB, 104, 184418 (2021)<br/>[2] “Spin-phonon relaxation from a universal ab initio density-matrix approach”, J. Xu, A. Habib, S. Kumar, F. Wu, R. Sundararaman, and Y. Ping Nat. Commun., 11, 2780, (2020)<br/>[3] “Giant spin lifetime anisotropy and spin-valley locking in silicene and germanene from first-principles density-matrix dynamics”, J. Xu et al, Y.Ping, Nano Lett. 21, 9594, (2021)<br/>[4] “Ab-initio Predictions of Spin Relaxation, Dephasing and Diffusion in Solids”, J. Xu and Y. Ping, J. Chem. Theory Comput., 20, 492, (2023)<br/>[5] “Substrate effects on spin relaxation in two-dimensional Dirac materials with strong spin-orbit coupling”, J. Xu and Y. Ping, <i>npj Computational Materials</i>, <b>9</b>, 47, (2023)<br/>[6] “How Spin Relaxes and Dephases in Bulk Halide Perovskites”, J. Xu, K. Li,<i> </i>U. Huynh, J. Huang, R. Sundararaman, V. Vardeny,<i> </i>and Y. Ping, Nat. Commun., 15, 188, (2024)<br/>[7] ”Circular Dichroism of Crystals from First Principles”, C. Multunas, A. Grieder, J. Xu, Y. Ping, R. Sundararaman, Phys. Rev. Mater., 7, 123801, (2023)